Commit graph

475 commits

Author SHA1 Message Date
Vladimir Davydov
7e3115ef51 sched/balancing: Fix cfs_rq->task_h_load calculation
Patch a003a2 (sched: Consider runnable load average in move_tasks())
sets all top-level cfs_rqs' h_load to rq->avg.load_avg_contrib, which is
always 0. This mistype leads to all tasks having weight 0 when load
balancing in a cpu-cgroup enabled setup. There obviously should be sum
of weights of all runnable tasks there instead. Fix it.

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Reviewed-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1379173186-11944-1-git-send-email-vdavydov@parallels.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-20 11:59:39 +02:00
Vladimir Davydov
3029ede393 sched/balancing: Fix 'local->avg_load > busiest->avg_load' case in fix_small_imbalance()
In busiest->group_imb case we can come to fix_small_imbalance() with
local->avg_load > busiest->avg_load. This can result in wrong imbalance
fix-up, because there is the following check there where all the
members are unsigned:

if (busiest->avg_load - local->avg_load + scaled_busy_load_per_task >=
    (scaled_busy_load_per_task * imbn)) {
	env->imbalance = busiest->load_per_task;
	return;
}

As a result we can end up constantly bouncing tasks from one cpu to
another if there are pinned tasks.

Fix it by substituting the subtraction with an equivalent addition in
the check.

[ The bug can be caught by running 2*N cpuhogs pinned to two logical cpus
  belonging to different cores on an HT-enabled machine with N logical
  cpus: just look at se.nr_migrations growth. ]

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/ef167822e5c5b2d96cf5b0e3e4f4bdff3f0414a2.1379252740.git.vdavydov@parallels.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-20 11:59:38 +02:00
Vladimir Davydov
b18855500f sched/balancing: Fix 'local->avg_load > sds->avg_load' case in calculate_imbalance()
In busiest->group_imb case we can come to calculate_imbalance() with
local->avg_load >= busiest->avg_load >= sds->avg_load. This can result
in imbalance overflow, because it is calculated as follows

env->imbalance = min(
	max_pull * busiest->group_power,
	(sds->avg_load - local->avg_load) * local->group_power) / SCHED_POWER_SCALE;

As a result we can end up constantly bouncing tasks from one cpu to
another if there are pinned tasks.

Fix this by skipping the assignment and assuming imbalance=0 in case
local->avg_load > sds->avg_load.

[ The bug can be caught by running 2*N cpuhogs pinned to two logical cpus
  belonging to different cores on an HT-enabled machine with N logical
  cpus: just look at se.nr_migrations growth. ]

Signed-off-by: Vladimir Davydov <vdavydov@parallels.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/8f596cc6bc0e5e655119dc892c9bfcad26e971f4.1379252740.git.vdavydov@parallels.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-20 11:59:36 +02:00
Linus Torvalds
7e28b2712e Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Misc fixes"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix comment for sched_info_depart
  sched/Documentation: Update sched-design-CFS.txt documentation
  sched/debug: Take PID namespace into account
  sched/fair: Fix small race where child->se.parent,cfs_rq might point to invalid ones
2013-09-18 11:23:32 -05:00
Michael S. Tsirkin
13b62e46d5 sched: Fix comment for sched_info_depart
sched_info_depart seems to be only called from
sched_info_switch(), so only on involuntary task switch.

Fix the comment to match.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Link: http://lkml.kernel.org/r/20130916083036.GA1113@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-16 11:18:34 +02:00
Linus Torvalds
b55ee2816e Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fix from Ingo Molnar:
 "Performance regression fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Fix load balancing performance regression in should_we_balance()
2013-09-12 10:44:13 -07:00
Peter Zijlstra
fc840914e9 sched/debug: Take PID namespace into account
Emmanuel reported that /proc/sched_debug didn't report the right PIDs
when using namespaces, cure this.

Reported-by: Emmanuel Deloget <emmanuel.deloget@efixo.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20130909110141.GM31370@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-12 19:14:16 +02:00
Daisuke Nishimura
6c9a27f5da sched/fair: Fix small race where child->se.parent,cfs_rq might point to invalid ones
There is a small race between copy_process() and cgroup_attach_task()
where child->se.parent,cfs_rq points to invalid (old) ones.

        parent doing fork()      | someone moving the parent to another cgroup
  -------------------------------+---------------------------------------------
    copy_process()
      + dup_task_struct()
        -> parent->se is copied to child->se.
           se.parent,cfs_rq of them point to old ones.

                                     cgroup_attach_task()
                                       + cgroup_task_migrate()
                                         -> parent->cgroup is updated.
                                       + cpu_cgroup_attach()
                                         + sched_move_task()
                                           + task_move_group_fair()
                                             +- set_task_rq()
                                                -> se.parent,cfs_rq of parent
                                                   are updated.

      + cgroup_fork()
        -> parent->cgroup is copied to child->cgroup. (*1)
      + sched_fork()
        + task_fork_fair()
          -> se.parent,cfs_rq of child are accessed
             while they point to old ones. (*2)

In the worst case, this bug can lead to "use-after-free" and cause a panic,
because it's new cgroup's refcount that is incremented at (*1),
so the old cgroup(and related data) can be freed before (*2).

In fact, a panic caused by this bug was originally caught in RHEL6.4.

    BUG: unable to handle kernel NULL pointer dereference at (null)
    IP: [<ffffffff81051e3e>] sched_slice+0x6e/0xa0
    [...]
    Call Trace:
     [<ffffffff81051f25>] place_entity+0x75/0xa0
     [<ffffffff81056a3a>] task_fork_fair+0xaa/0x160
     [<ffffffff81063c0b>] sched_fork+0x6b/0x140
     [<ffffffff8106c3c2>] copy_process+0x5b2/0x1450
     [<ffffffff81063b49>] ? wake_up_new_task+0xd9/0x130
     [<ffffffff8106d2f4>] do_fork+0x94/0x460
     [<ffffffff81072a9e>] ? sys_wait4+0xae/0x100
     [<ffffffff81009598>] sys_clone+0x28/0x30
     [<ffffffff8100b393>] stub_clone+0x13/0x20
     [<ffffffff8100b072>] ? system_call_fastpath+0x16/0x1b

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: <stable@vger.kernel.org>
Link: http://lkml.kernel.org/r/039601ceae06$733d3130$59b79390$@mxp.nes.nec.co.jp
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-12 19:14:14 +02:00
Joonsoo Kim
b0cff9d88c sched: Fix load balancing performance regression in should_we_balance()
Commit 23f0d20 ("sched: Factor out code to should_we_balance()")
introduces the should_we_balance() function.  This function should
return 1 if this cpu is appropriate for balancing. But the newly
introduced code doesn't do so, it returns 0 instead of 1.

This introduces performance regression, reported by Dave Chinner:

                        v4 filesystem           v5 filesystem
3.11+xfsdev:            220k files/s            225k files/s
3.12-git                180k files/s            185k files/s
3.12-git-revert         245k files/s            247k files/s

You can find more detailed information at:

  https://lkml.org/lkml/2013/9/10/1

This patch corrects the return value of should_we_balance()
function as orignally intended.

With this patch, Dave Chinner reports that the regression is gone:

                        v4 filesystem           v5 filesystem
3.11+xfsdev:            220k files/s            225k files/s
3.12-git                180k files/s            185k files/s
3.12-git-revert         245k files/s            247k files/s
3.12-git-fix            249k files/s            248k files/s

Reported-by: Dave Chinner <dchinner@redhat.com>
Tested-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Link: http://lkml.kernel.org/r/20130910065448.GA20368@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-10 09:20:42 +02:00
Linus Torvalds
57d730924d Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull cputime fix from Ingo Molnar:
 "This fixes a longer-standing cputime accounting bug that Stanislaw
  Gruszka finally managed to track down"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/cputime: Do not scale when utime == 0
2013-09-05 12:36:46 -07:00
Linus Torvalds
ae7a835cc5 Merge branch 'next' of git://git.kernel.org/pub/scm/virt/kvm/kvm
Pull KVM updates from Gleb Natapov:
 "The highlights of the release are nested EPT and pv-ticketlocks
  support (hypervisor part, guest part, which is most of the code, goes
  through tip tree).  Apart of that there are many fixes for all arches"

Fix up semantic conflicts as discussed in the pull request thread..

* 'next' of git://git.kernel.org/pub/scm/virt/kvm/kvm: (88 commits)
  ARM: KVM: Add newlines to panic strings
  ARM: KVM: Work around older compiler bug
  ARM: KVM: Simplify tracepoint text
  ARM: KVM: Fix kvm_set_pte assignment
  ARM: KVM: vgic: Bump VGIC_NR_IRQS to 256
  ARM: KVM: Bugfix: vgic_bytemap_get_reg per cpu regs
  ARM: KVM: vgic: fix GICD_ICFGRn access
  ARM: KVM: vgic: simplify vgic_get_target_reg
  KVM: MMU: remove unused parameter
  KVM: PPC: Book3S PR: Rework kvmppc_mmu_book3s_64_xlate()
  KVM: PPC: Book3S PR: Make instruction fetch fallback work for system calls
  KVM: PPC: Book3S PR: Don't corrupt guest state when kernel uses VMX
  KVM: x86: update masterclock when kvmclock_offset is calculated (v2)
  KVM: PPC: Book3S: Fix compile error in XICS emulation
  KVM: PPC: Book3S PR: return appropriate error when allocation fails
  arch: powerpc: kvm: add signed type cast for comparation
  KVM: x86: add comments where MMIO does not return to the emulator
  KVM: vmx: count exits to userspace during invalid guest emulation
  KVM: rename __kvm_io_bus_sort_cmp to kvm_io_bus_cmp
  kvm: optimize away THP checks in kvm_is_mmio_pfn()
  ...
2013-09-04 18:15:06 -07:00
Linus Torvalds
6832d9652f Merge branch 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull timers/nohz changes from Ingo Molnar:
 "It mostly contains fixes and full dynticks off-case optimizations, by
  Frederic Weisbecker"

* 'timers-nohz-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  nohz: Include local CPU in full dynticks global kick
  nohz: Optimize full dynticks's sched hooks with static keys
  nohz: Optimize full dynticks state checks with static keys
  nohz: Rename a few state variables
  vtime: Always debug check snapshot source _before_ updating it
  vtime: Always scale generic vtime accounting results
  vtime: Optimize full dynticks accounting off case with static keys
  vtime: Describe overriden functions in dedicated arch headers
  m68k: hardirq_count() only need preempt_mask.h
  hardirq: Split preempt count mask definitions
  context_tracking: Split low level state headers
  vtime: Fix racy cputime delta update
  vtime: Remove a few unneeded generic vtime state checks
  context_tracking: User/kernel broundary cross trace events
  context_tracking: Optimize context switch off case with static keys
  context_tracking: Optimize guest APIs off case with static key
  context_tracking: Optimize main APIs off case with static key
  context_tracking: Ground setup for static key use
  context_tracking: Remove full dynticks' hacky dependency on wide context tracking
  nohz: Only enable context tracking on full dynticks CPUs
  ...
2013-09-04 09:36:54 -07:00
Linus Torvalds
5e0b3a4e88 Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler changes from Ingo Molnar:
 "Various optimizations, cleanups and smaller fixes - no major changes
  in scheduler behavior"

* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/fair: Fix the sd_parent_degenerate() code
  sched/fair: Rework and comment the group_imb code
  sched/fair: Optimize find_busiest_queue()
  sched/fair: Make group power more consistent
  sched/fair: Remove duplicate load_per_task computations
  sched/fair: Shrink sg_lb_stats and play memset games
  sched: Clean-up struct sd_lb_stat
  sched: Factor out code to should_we_balance()
  sched: Remove one division operation in find_busiest_queue()
  sched/cputime: Use this_cpu_add() in task_group_account_field()
  cpumask: Fix cpumask leak in partition_sched_domains()
  sched/x86: Optimize switch_mm() for multi-threaded workloads
  generic-ipi: Kill unnecessary variable - csd_flags
  numa: Mark __node_set() as __always_inline
  sched/fair: Cleanup: remove duplicate variable declaration
  sched/__wake_up_sync_key(): Fix nr_exclusive tasks which lead to WF_SYNC clearing
2013-09-04 08:36:35 -07:00
Linus Torvalds
0d99b70873 Merge branches 'perf-urgent-for-linus' and 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull perf changes from Ingo Molnar:
 "As a first remark I'd like to point out that the obsolete '-f'
  (--force) option, which has not done anything for several releases,
  has been removed from 'perf record' and related utilities.  Everyone
  please update muscle memory accordingly! :-)

  Main changes on the perf kernel side:

   - Performance optimizations:
        . for trace events, by Steve Rostedt.
        . for time values, by Peter Zijlstra

   - New hardware support:
        . for Intel Silvermont (22nm Atom) CPUs, by Zheng Yan
        . for Intel SNB-EP uncore PMUs, by Zheng Yan

   - Enhanced hardware support:
        . for Intel uncore PMUs: add filter support for QPI boxes, by Zheng Yan

   - Core perf events code enhancements and fixes:
        . for full-nohz feature handling, by Frederic Weisbecker
        . for group events, by Jiri Olsa
        . for call chains, by Frederic Weisbecker
        . for event stream parsing, by Adrian Hunter

   - New ABI details:
        . Add attr->mmap2 attribute, by Stephane Eranian
        . Add PERF_EVENT_IOC_ID ioctl to return event ID, by Jiri Olsa
        . Export u64 time_zero on the mmap header page to allow TSC
          calculation, by Adrian Hunter
        . Add dummy software event, by Adrian Hunter.
        . Add a new PERF_SAMPLE_IDENTIFIER to make samples always
          parseable, by Adrian Hunter.
        . Make Power7 events available via sysfs, by Runzhen Wang.

   - Code cleanups and refactorings:
        . for nohz-full, by Frederic Weisbecker
        . for group events, by Jiri Olsa

   - Documentation updates:
        . for perf_event_type, by Peter Zijlstra

  Main changes on the perf tooling side (some of these tooling changes
  utilize the above kernel side changes):

   - Lots of 'perf trace' enhancements:

        . Make 'perf trace' command line arguments consistent with
          'perf record', by David Ahern.

        . Allow specifying syscalls a la strace, by Arnaldo Carvalho de Melo.

        . Add --verbose and -o/--output options, by Arnaldo Carvalho de Melo.

        . Support ! in -e expressions, to filter a list of syscalls,
          by Arnaldo Carvalho de Melo.

        . Arg formatting improvements to allow masking arguments in
          syscalls such as futex and open, where the some arguments are
          ignored and thus should not be printed depending on other args,
          by Arnaldo Carvalho de Melo.

        . Beautify futex open, openat, open_by_handle_at, lseek and futex
          syscalls, by Arnaldo Carvalho de Melo.

        . Add option to analyze events in a file versus live, so that
          one can do:

           [root@zoo ~]# perf record -a -e raw_syscalls:* sleep 1
           [ perf record: Woken up 0 times to write data ]
           [ perf record: Captured and wrote 25.150 MB perf.data (~1098836 samples) ]
           [root@zoo ~]# perf trace -i perf.data -e futex --duration 1
              17.799 ( 1.020 ms): 7127 futex(uaddr: 0x7fff3f6c6674, op: 393, val: 1, utime: 0x7fff3f6c6470, ua
             113.344 (95.429 ms): 7127 futex(uaddr: 0x7fff3f6c6674, op: 393, val: 1, utime: 0x7fff3f6c6470, uaddr2: 0x7fff3f6c6648, val3: 4294967
             133.778 ( 1.042 ms): 18004 futex(uaddr: 0x7fff3f6c6674, op: 393, val: 1, utime: 0x7fff3f6c6470, uaddr2: 0x7fff3f6c6648, val3: 429496
           [root@zoo ~]#

          By David Ahern.

        . Honor target pid / tid options when analyzing a file, by David Ahern.

        . Introduce better formatting of syscall arguments, including so
          far beautifiers for mmap, madvise, syscall return values,
          by Arnaldo Carvalho de Melo.

        . Handle HUGEPAGE defines in the mmap beautifier, by David Ahern.

   - 'perf report/top' enhancements:

        . Do annotation using /proc/kcore and /proc/kallsyms when
          available, removing the forced need for a vmlinux file kernel
          assembly annotation. This also improves this use case because
          vmlinux has just the initial kernel image, not what is actually
          in use after various code patchings by things like alternatives.
          By Adrian Hunter.

        . Add --ignore-callees=<regex> option to collapse undesired parts
          of call graphs, by Greg Price.

        . Simplify symbol filtering by doing it at machine class level,
          by Adrian Hunter.

        . Add support for callchains in the gtk UI, by Namhyung Kim.

        . Add --objdump option to 'perf top', by Sukadev Bhattiprolu.

   - 'perf kvm' enhancements:

        . Add option to print only events that exceed a specified time
          duration, by David Ahern.

        . Improve stack trace printing, by David Ahern.

        . Update documentation of the live command, by David Ahern

        . Add perf kvm stat live mode that combines aspects of 'perf kvm
          stat' record and report, by David Ahern.

        . Add option to analyze specific VM in perf kvm stat report, by
          David Ahern.

        . Do not require /lib/modules/* on a guest, by Jason Wessel.

   - 'perf script' enhancements:

        . Fix symbol offset computation for some dsos, by David Ahern.

        . Fix named threads support, by David Ahern.

        . Don't install scripting files files when perl/python support
          is disabled, by Arnaldo Carvalho de Melo.

   - 'perf test' enhancements:

        . Add various improvements and fixes to the "vmlinux matches
          kallsyms" 'perf test' entry, related to the /proc/kcore
          annotation feature. By Adrian Hunter.

        . Add sample parsing test, by Adrian Hunter.

        . Add test for reading object code, by Adrian Hunter.

        . Add attr record group sampling test, by Jiri Olsa.

        . Misc testing infrastructure improvements and other details,
          by Jiri Olsa.

   - 'perf list' enhancements:

        . Skip unsupported hardware events, by Namhyung Kim.

        . List pmu events, by Andi Kleen.

   - 'perf diff' enhancements:

        . Add support for more than two files comparison, by Jiri Olsa.

   - 'perf sched' enhancements:

        . Various improvements, including removing reliance on some
          scheduler tracepoints that provide the same information as the
          PERF_RECORD_{FORK,EXIT} events. By David Ahern.

        . Remove odd build stall by moving a large struct initialization
          from a local variable to a global one, by Namhyung Kim.

   - 'perf stat' enhancements:

        . Add --initial-delay option to skip measuring for a defined
          startup phase, by Andi Kleen.

   - Generic perf tooling infrastructure/plumbing changes:

        . Tidy up sample parsing validation, by Adrian Hunter.

        . Fix up jobserver setup in libtraceevent Makefile.
          by Arnaldo Carvalho de Melo.

        . Debug improvements, by Adrian Hunter.

        . Fix correlation of samples coming after PERF_RECORD_EXIT event,
          by David Ahern.

        . Improve robustness of the topology parsing code,
          by Stephane Eranian.

        . Add group leader sampling, that allows just one event in a group
          to sample while the other events have just its values read,
          by Jiri Olsa.

        . Add support for a new modifier "D", which requests that the
          event, or group of events, be pinned to the PMU.
          By Michael Ellerman.

        . Support callchain sorting based on addresses, by Andi Kleen

        . Prep work for multi perf data file storage, by Jiri Olsa.

        . libtraceevent cleanups, by Namhyung Kim.

  And lots and lots of other fixes and code reorganizations that did not
  make it into the list, see the shortlog, diffstat and the Git log for
  details!"

[ Also merge a leftover from the 3.11 cycle ]

* 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  perf: Prevent race in unthrottling code

* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (237 commits)
  perf trace: Tell arg formatters the arg index
  perf trace: Add beautifier for open's flags arg
  perf trace: Add beautifier for lseek's whence arg
  perf tools: Fix symbol offset computation for some dsos
  perf list: Skip unsupported events
  perf tests: Add 'keep tracking' test
  perf tools: Add support for PERF_COUNT_SW_DUMMY
  perf: Add a dummy software event to keep tracking
  perf trace: Add beautifier for futex 'operation' parm
  perf trace: Allow syscall arg formatters to mask args
  perf: Convert kmalloc_node(...GFP_ZERO...) to kzalloc_node()
  perf: Export struct perf_branch_entry to userspace
  perf: Add attr->mmap2 attribute to an event
  perf/x86: Add Silvermont (22nm Atom) support
  perf/x86: use INTEL_UEVENT_EXTRA_REG to define MSR_OFFCORE_RSP_X
  perf trace: Handle missing HUGEPAGE defines
  perf trace: Honor target pid / tid options when analyzing a file
  perf trace: Add option to analyze events in a file versus live
  perf evlist: Add tracepoint lookup by name
  perf tests: Add a sample parsing test
  ...
2013-09-04 08:25:35 -07:00
Stanislaw Gruszka
5a8e01f8fa sched/cputime: Do not scale when utime == 0
scale_stime() silently assumes that stime < rtime, otherwise
when stime == rtime and both values are big enough (operations
on them do not fit in 32 bits), the resulting scaling stime can
be bigger than rtime. In consequence utime = rtime - stime
results in negative value.

User space visible symptoms of the bug are overflowed TIME
values on ps/top, for example:

 $ ps aux | grep rcu
 root         8  0.0  0.0      0     0 ?        S    12:42   0:00 [rcuc/0]
 root         9  0.0  0.0      0     0 ?        S    12:42   0:00 [rcub/0]
 root        10 62422329  0.0  0     0 ?        R    12:42 21114581:37 [rcu_preempt]
 root        11  0.1  0.0      0     0 ?        S    12:42   0:02 [rcuop/0]
 root        12 62422329  0.0  0     0 ?        S    12:42 21114581:35 [rcuop/1]
 root        10 62422329  0.0  0     0 ?        R    12:42 21114581:37 [rcu_preempt]

or overflowed utime values read directly from /proc/$PID/stat

Reference:

  https://lkml.org/lkml/2013/8/20/259

Reported-and-tested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: stable@vger.kernel.org
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Link: http://lkml.kernel.org/r/20130904131602.GC2564@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-04 16:31:25 +02:00
Linus Torvalds
32dad03d16 Merge branch 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo:
 "A lot of activities on the cgroup front.  Most changes aren't visible
  to userland at all at this point and are laying foundation for the
  planned unified hierarchy.

   - The biggest change is decoupling the lifetime management of css
     (cgroup_subsys_state) from that of cgroup's.  Because controllers
     (cpu, memory, block and so on) will need to be dynamically enabled
     and disabled, css which is the association point between a cgroup
     and a controller may come and go dynamically across the lifetime of
     a cgroup.  Till now, css's were created when the associated cgroup
     was created and stayed till the cgroup got destroyed.

     Assumptions around this tight coupling permeated through cgroup
     core and controllers.  These assumptions are gradually removed,
     which consists bulk of patches, and css destruction path is
     completely decoupled from cgroup destruction path.  Note that
     decoupling of creation path is relatively easy on top of these
     changes and the patchset is pending for the next window.

   - cgroup has its own event mechanism cgroup.event_control, which is
     only used by memcg.  It is overly complex trying to achieve high
     flexibility whose benefits seem dubious at best.  Going forward,
     new events will simply generate file modified event and the
     existing mechanism is being made specific to memcg.  This pull
     request contains prepatory patches for such change.

   - Various fixes and cleanups"

Fixed up conflict in kernel/cgroup.c as per Tejun.

* 'for-3.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: (69 commits)
  cgroup: fix cgroup_css() invocation in css_from_id()
  cgroup: make cgroup_write_event_control() use css_from_dir() instead of __d_cgrp()
  cgroup: make cgroup_event hold onto cgroup_subsys_state instead of cgroup
  cgroup: implement CFTYPE_NO_PREFIX
  cgroup: make cgroup_css() take cgroup_subsys * instead and allow NULL subsys
  cgroup: rename cgroup_css_from_dir() to css_from_dir() and update its syntax
  cgroup: fix cgroup_write_event_control()
  cgroup: fix subsystem file accesses on the root cgroup
  cgroup: change cgroup_from_id() to css_from_id()
  cgroup: use css_get() in cgroup_create() to check CSS_ROOT
  cpuset: remove an unncessary forward declaration
  cgroup: RCU protect each cgroup_subsys_state release
  cgroup: move subsys file removal to kill_css()
  cgroup: factor out kill_css()
  cgroup: decouple cgroup_subsys_state destruction from cgroup destruction
  cgroup: replace cgroup->css_kill_cnt with ->nr_css
  cgroup: bounce cgroup_subsys_state ref kill confirmation to a work item
  cgroup: move cgroup->subsys[] assignment to online_css()
  cgroup: reorganize css init / exit paths
  cgroup: add __rcu modifier to cgroup->subsys[]
  ...
2013-09-03 18:25:03 -07:00
Peter Zijlstra
10866e62e8 sched/fair: Fix the sd_parent_degenerate() code
I found that on my WSM box I had a redundant domain:

[    0.949769] CPU0 attaching sched-domain:
[    0.953765]  domain 0: span 0,12 level SIBLING
[    0.958335]   groups: 0 (cpu_power = 587) 12 (cpu_power = 588)
[    0.964548]   domain 1: span 0-5,12-17 level MC
[    0.969206]    groups: 0,12 (cpu_power = 1175) 1,13 (cpu_power = 1176) 2,14 (cpu_power = 1176) 3,15 (cpu_power = 1176) 4,16 (cpu_power = 1176) 5,17 (cpu_power = 1176)
[    0.984993]    domain 2: span 0-5,12-17 level CPU
[    0.989822]     groups: 0-5,12-17 (cpu_power = 7055)
[    0.995049]     domain 3: span 0-23 level NUMA
[    0.999620]      groups: 0-5,12-17 (cpu_power = 7055) 6-11,18-23 (cpu_power = 7056)

Note how domain 2 has only a single group and spans the same CPUs as
domain 1. We should not keep such domains and do in fact have code to
prune these.

It turns out that the 'new' SD_PREFER_SIBLING flag causes this, it
makes sd_parent_degenerate() fail on the CPU domain. We can easily
fix this by 'ignoring' the SD_PREFER_SIBLING bit and transfering it
to whatever domain ends up covering the span.

With this patch the domains now look like this:

[    0.950419] CPU0 attaching sched-domain:
[    0.954454]  domain 0: span 0,12 level SIBLING
[    0.959039]   groups: 0 (cpu_power = 587) 12 (cpu_power = 588)
[    0.965271]   domain 1: span 0-5,12-17 level MC
[    0.969936]    groups: 0,12 (cpu_power = 1175) 1,13 (cpu_power = 1176) 2,14 (cpu_power = 1176) 3,15 (cpu_power = 1176) 4,16 (cpu_power = 1176) 5,17 (cpu_power = 1176)
[    0.985737]    domain 2: span 0-23 level NUMA
[    0.990231]     groups: 0-5,12-17 (cpu_power = 7055) 6-11,18-23 (cpu_power = 7056)

Reviewed-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-ys201g4jwukj0h8xcamakxq1@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:27:40 +02:00
Peter Zijlstra
30ce5dabc9 sched/fair: Rework and comment the group_imb code
Rik reported some weirdness due to the group_imb code. As a start to
looking at it, clean it up a little and add a few explanatory
comments.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-caeeqttnla4wrrmhp5uf89gp@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:27:38 +02:00
Peter Zijlstra
6906a40839 sched/fair: Optimize find_busiest_queue()
Use for_each_cpu_and() and thereby avoid computing the capacity for
CPUs we know we're not interested in.

Reviewed-by: Paul Turner <pjt@google.com>
Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-lppceyv6kb3a19g8spmrn20b@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:27:37 +02:00
Peter Zijlstra
3ae11c90fd sched/fair: Make group power more consistent
For easier access, less dereferences and more consistent value, store
the group power in update_sg_lb_stats() and use it thereafter. The
actual value in sched_group::sched_group_power::power can change
throughout the load-balance pass if we're unlucky.

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-739xxqkyvftrhnh9ncudutc7@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:27:37 +02:00
Peter Zijlstra
38d0f77085 sched/fair: Remove duplicate load_per_task computations
Since we already compute (but don't store) the sgs load_per_task value
in update_sg_lb_stats() we might as well store it and not re-compute
it later on.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-ym1vmljiwbzgdnnrwp9azftq@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:27:36 +02:00
Peter Zijlstra
147c5fc2ba sched/fair: Shrink sg_lb_stats and play memset games
We can shrink sg_lb_stats because rq::nr_running is an unsigned int
and cpu numbers are 'int'

Before:
  sgs:        /* size: 72, cachelines: 2, members: 10 */
  sds:        /* size: 184, cachelines: 3, members: 7 */

After:
  sgs:        /* size: 56, cachelines: 1, members: 10 */
  sds:        /* size: 152, cachelines: 3, members: 7 */

Further we can avoid clearing all of sds since we do a total
clear/assignment of sg_stats in update_sg_lb_stats() with exception of
busiest_stat.avg_load which is referenced in update_sd_pick_busiest().

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/tip-0klzmz9okll8wc0nsudguc9p@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:27:35 +02:00
Joonsoo Kim
56cf515b4b sched: Clean-up struct sd_lb_stat
There is no reason to maintain separate variables for this_group
and busiest_group in sd_lb_stat, except saving some space.
But this structure is always allocated in stack, so this saving
isn't really benificial [peterz: reducing stack space is good; in this
case readability increases enough that I think its still beneficial]

This patch unify these variables, so IMO, readability may be improved.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
[ Rename this to local -- avoids confusion between this_cpu and the C++ this pointer. ]
Reviewed-by: Paul  Turner <pjt@google.com>
[ Lots of style edits, a few fixes and a rename. ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375778203-31343-4-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:27:35 +02:00
Joonsoo Kim
23f0d2093c sched: Factor out code to should_we_balance()
Now checking whether this cpu is appropriate to balance or not
is embedded into update_sg_lb_stats() and this checking has no direct
relationship to this function. There is not enough reason to place
this checking at update_sg_lb_stats(), except saving one iteration
for sched_group_cpus.

In this patch, I factor out this checking to should_we_balance() function.
And before doing actual work for load_balancing, check whether this cpu is
appropriate to balance via should_we_balance(). If this cpu is not
a candidate for balancing, it quit the work immediately.

With this change, we can save two memset cost and can expect better
compiler optimization.

Below is result of this patch.

 * Vanilla *
   text	   data	    bss	    dec	    hex	filename
  34499	   1136	    116	  35751	   8ba7	kernel/sched/fair.o

 * Patched *
   text	   data	    bss	    dec	    hex	filename
  34243	   1136	    116	  35495	   8aa7	kernel/sched/fair.o

In addition, rename @balance to @continue_balancing in order to represent
its purpose more clearly.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
[ s/should_balance/continue_balancing/g ]
Reviewed-by: Paul Turner <pjt@google.com>
[ Made style changes and a fix in should_we_balance(). ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375778203-31343-3-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:27:34 +02:00
Joonsoo Kim
95a79b805b sched: Remove one division operation in find_busiest_queue()
Remove one division operation in find_busiest_queue() by using
crosswise multiplication:

	wl_i / power_i > wl_j / power_j :=
	wl_i * power_j > wl_j * power_i

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
[ Expanded the changelog. ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375778203-31343-2-git-send-email-iamjoonsoo.kim@lge.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-09-02 08:26:59 +02:00
Ingo Molnar
aee2bce3cf Merge branch 'linus' into perf/core
Pick up the latest upstream fixes.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-08-29 12:02:08 +02:00
Christoph Lameter
a4f61cc03e sched/cputime: Use this_cpu_add() in task_group_account_field()
Use of a this_cpu() operation reduces the number of instructions used
for accounting (account_user_time()) and frees up some registers. This is in
the scheduler tick hotpath.

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/00000140596dd165-338ff7f5-893b-4fec-b251-aaac5557239e-000000@email.amazonses.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-08-16 17:44:29 +02:00
Xiaotian Feng
c8d2d47a9c cpumask: Fix cpumask leak in partition_sched_domains()
If doms_new is NULL, partition_sched_domains() will reset ndoms_cur
to 0, and free old sched domains with free_sched_domains(doms_cur, ndoms_cur).
As ndoms_cur is 0, the cpumask will not be freed.

Signed-off-by: Xiaotian Feng <xtfeng@gmail.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1375790802-11857-1-git-send-email-xtfeng@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-08-16 17:44:27 +02:00
Ingo Molnar
d3ec3a1fd0 Linux 3.11-rc5
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Merge tag 'v3.11-rc5' into sched/core

Merge Linux 3.11-rc5, to pick up the latest fixes.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-08-16 17:40:23 +02:00
Ingo Molnar
c9572f010d Linux 3.11-rc5
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Merge tag 'v3.11-rc5' into perf/core

Merge Linux 3.11-rc5, to sync up with the latest upstream fixes since -rc1.

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-08-15 10:00:09 +02:00
Ingo Molnar
6f1d657668 Merge branch 'timers/nohz-v3' of git://git.kernel.org/pub/scm/linux/kernel/git/frederic/linux-dynticks into timers/nohz
Pull nohz improvements from Frederic Weisbecker:

 " It mostly contains fixes and full dynticks off-case optimizations. I believe that
   distros want to enable this feature so it seems important to optimize the case
   where the "nohz_full=" parameter is empty. ie: I'm trying to remove any performance
   regression that comes with NO_HZ_FULL=y when the feature is not used.

   This patchset improves the current situation a lot (off-case appears to be around 11% faster
   with hackbench, although I guess it may vary depending on the configuration but it should be
   significantly faster in any case) now there is still some work to do: I can still observe a
   remaining loss of 1.6% throughput seen with hackbench compared to CONFIG_NO_HZ_FULL=n. "

Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-08-14 17:58:56 +02:00
Frederic Weisbecker
af2350bd12 vtime: Always debug check snapshot source _before_ updating it
The vtime delta update performed by get_vtime_delta() always check
that the source of the snapshot is valid.

Meanhile the snapshot updaters that rely on get_vtime_delta() also
set the new snapshot origin. But some of them do this right before
the call to get_vtime_delta(), making its debug check useless.

This is easily fixable by moving the snapshot origin update after
the call to get_vtime_delta(). The order doesn't matter there.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
2013-08-14 17:14:56 +02:00
Frederic Weisbecker
b854fafa4e vtime: Always scale generic vtime accounting results
The cputime accounting in full dynticks can be a subtle
mixup of CPUs using tick based accounting and others using
generic vtime.

As long as the tick can have a share on producing these stats, we
want to scale the result against CFS precise accounting as the tick
can miss some task hiding between the periodic interrupt.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
2013-08-14 17:14:55 +02:00
Frederic Weisbecker
b049340613 vtime: Optimize full dynticks accounting off case with static keys
If no CPU is in the full dynticks range, we can avoid the full
dynticks cputime accounting through generic vtime along with its
overhead and use the traditional tick based accounting instead.

Let's do this and nope the off case with static keys.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
2013-08-14 17:14:54 +02:00
Frederic Weisbecker
54461562c9 vtime: Fix racy cputime delta update
get_vtime_delta() must be called under the task vtime_seqlock
with the code that does the cputime accounting flush.

Otherwise the cputime reader can be fooled and run into
a race where it sees the snapshot update but misses the
cputime flush. As a result it can report a cputime that is
way too short.

Fix vtime_account_user() that wasn't complying to that rule.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
2013-08-14 17:14:50 +02:00
Frederic Weisbecker
7621d1f8bc vtime: Remove a few unneeded generic vtime state checks
Some generic vtime APIs check if the vtime accounting
is enabled on the local CPU before doing their work.

Some of these are not needed because all their callers already
take care of that. Let's remove the checks on these.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
2013-08-14 17:14:49 +02:00
Frederic Weisbecker
48d6a816a8 context_tracking: Optimize guest APIs off case with static key
Optimize guest entry/exit APIs with static keys. This minimize
the overhead for those who enable CONFIG_NO_HZ_FULL without
always using it. Having no range passed to nohz_full= should
result in the probes overhead to be minimized.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
2013-08-14 17:14:46 +02:00
Linus Torvalds
28fbc8b6a2 Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull scheduler fixes from Ingo Molnar:
 "Docbook fixes that make 99% of the diffstat, plus a oneliner fix"

* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched: Ensure update_cfs_shares() is called for parents of continuously-running tasks
  sched: Fix some kernel-doc warnings
2013-08-13 16:58:17 -07:00
Oleg Nesterov
e0acd0a68e sched: fix the theoretical signal_wake_up() vs schedule() race
This is only theoretical, but after try_to_wake_up(p) was changed
to check p->state under p->pi_lock the code like

	__set_current_state(TASK_INTERRUPTIBLE);
	schedule();

can miss a signal. This is the special case of wait-for-condition,
it relies on try_to_wake_up/schedule interaction and thus it does
not need mb() between __set_current_state() and if(signal_pending).

However, this __set_current_state() can move into the critical
section protected by rq->lock, now that try_to_wake_up() takes
another lock we need to ensure that it can't be reordered with
"if (signal_pending(current))" check inside that section.

The patch is actually one-liner, it simply adds smp_wmb() before
spin_lock_irq(rq->lock). This is what try_to_wake_up() already
does by the same reason.

We turn this wmb() into the new helper, smp_mb__before_spinlock(),
for better documentation and to allow the architectures to change
the default implementation.

While at it, kill smp_mb__after_lock(), it has no callers.

Perhaps we can also add smp_mb__before/after_spinunlock() for
prepare_to_wait().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-08-13 08:19:26 -07:00
Frederic Weisbecker
5b206d48e5 vtime: Update a few comments
Update a stale comment from the old vtime era and document some
locking that might be non obvious.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Kevin Hilman <khilman@linaro.org>
2013-08-13 00:40:44 +02:00
Frederic Weisbecker
fbb00b568b sched: Consolidate open coded preemptible() checks
preempt_schedule() and preempt_schedule_context() open
code their preemptability checks.

Use the standard API instead for consolidation.

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Alex Shi <alex.shi@intel.com>
Cc: Paul Turner <pjt@google.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Vincent Guittot <vincent.guittot@linaro.org>
2013-08-13 00:40:43 +02:00
Tejun Heo
d99c8727e7 cgroup: make cgroup_taskset deal with cgroup_subsys_state instead of cgroup
cgroup is in the process of converting to css (cgroup_subsys_state)
from cgroup as the principal subsystem interface handle.  This is
mostly to prepare for the unified hierarchy support where css's will
be created and destroyed dynamically but also helps cleaning up
subsystem implementations as css is usually what they are interested
in anyway.

cgroup_taskset which is used by the subsystem attach methods is the
last cgroup subsystem API which isn't using css as the handle.  Update
cgroup_taskset_cur_cgroup() to cgroup_taskset_cur_css() and
cgroup_taskset_for_each() to take @skip_css instead of @skip_cgrp.

The conversions are pretty mechanical.  One exception is
cpuset::cgroup_cs(), which lost its last user and got removed.

This patch shouldn't introduce any functional changes.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-08 20:11:27 -04:00
Tejun Heo
182446d087 cgroup: pass around cgroup_subsys_state instead of cgroup in file methods
cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup.
Please see the previous commit which converts the subsystem methods
for rationale.

This patch converts all cftype file operations to take @css instead of
@cgroup.  cftypes for the cgroup core files don't have their subsytem
pointer set.  These will automatically use the dummy_css added by the
previous patch and can be converted the same way.

Most subsystem conversions are straight forwards but there are some
interesting ones.

* freezer: update_if_frozen() is also converted to take @css instead
  of @cgroup for consistency.  This will make the code look simpler
  too once iterators are converted to use css.

* memory/vmpressure: mem_cgroup_from_css() needs to be exported to
  vmpressure while mem_cgroup_from_cont() can be made static.
  Updated accordingly.

* cpu: cgroup_tg() doesn't have any user left.  Removed.

* cpuacct: cgroup_ca() doesn't have any user left.  Removed.

* hugetlb: hugetlb_cgroup_form_cgroup() doesn't have any user left.
  Removed.

* net_cls: cgrp_cls_state() doesn't have any user left.  Removed.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-08 20:11:24 -04:00
Tejun Heo
eb95419b02 cgroup: pass around cgroup_subsys_state instead of cgroup in subsystem methods
cgroup is currently in the process of transitioning to using struct
cgroup_subsys_state * as the primary handle instead of struct cgroup *
in subsystem implementations for the following reasons.

* With unified hierarchy, subsystems will be dynamically bound and
  unbound from cgroups and thus css's (cgroup_subsys_state) may be
  created and destroyed dynamically over the lifetime of a cgroup,
  which is different from the current state where all css's are
  allocated and destroyed together with the associated cgroup.  This
  in turn means that cgroup_css() should be synchronized and may
  return NULL, making it more cumbersome to use.

* Differing levels of per-subsystem granularity in the unified
  hierarchy means that the task and descendant iterators should behave
  differently depending on the specific subsystem the iteration is
  being performed for.

* In majority of the cases, subsystems only care about its part in the
  cgroup hierarchy - ie. the hierarchy of css's.  Subsystem methods
  often obtain the matching css pointer from the cgroup and don't
  bother with the cgroup pointer itself.  Passing around css fits
  much better.

This patch converts all cgroup_subsys methods to take @css instead of
@cgroup.  The conversions are mostly straight-forward.  A few
noteworthy changes are

* ->css_alloc() now takes css of the parent cgroup rather than the
  pointer to the new cgroup as the css for the new cgroup doesn't
  exist yet.  Knowing the parent css is enough for all the existing
  subsystems.

* In kernel/cgroup.c::offline_css(), unnecessary open coded css
  dereference is replaced with local variable access.

This patch shouldn't cause any behavior differences.

v2: Unnecessary explicit cgrp->subsys[] deref in css_online() replaced
    with local variable @css as suggested by Li Zefan.

    Rebased on top of new for-3.12 which includes for-3.11-fixes so
    that ->css_free() invocation added by da0a12caff ("cgroup: fix a
    leak when percpu_ref_init() fails") is converted too.  Suggested
    by Li Zefan.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Vivek Goyal <vgoyal@redhat.com>
Acked-by: Aristeu Rozanski <aris@redhat.com>
Acked-by: Daniel Wagner <daniel.wagner@bmw-carit.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Steven Rostedt <rostedt@goodmis.org>
2013-08-08 20:11:23 -04:00
Tejun Heo
6387698699 cgroup: add css_parent()
Currently, controllers have to explicitly follow the cgroup hierarchy
to find the parent of a given css.  cgroup is moving towards using
cgroup_subsys_state as the main controller interface construct, so
let's provide a way to climb the hierarchy using just csses.

This patch implements css_parent() which, given a css, returns its
parent.  The function is guarnateed to valid non-NULL parent css as
long as the target css is not at the top of the hierarchy.

freezer, cpuset, cpu, cpuacct, hugetlb, memory, net_cls and devices
are converted to use css_parent() instead of accessing cgroup->parent
directly.

* __parent_ca() is dropped from cpuacct and its usage is replaced with
  parent_ca().  The only difference between the two was NULL test on
  cgroup->parent which is now embedded in css_parent() making the
  distinction moot.  Note that eventually a css->parent field will be
  added to css and the NULL check in css_parent() will go away.

This patch shouldn't cause any behavior differences.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-08 20:11:23 -04:00
Tejun Heo
a7c6d554aa cgroup: add/update accessors which obtain subsys specific data from css
css (cgroup_subsys_state) is usually embedded in a subsys specific
data structure.  Subsystems either use container_of() directly to cast
from css to such data structure or has an accessor function wrapping
such cast.  As cgroup as whole is moving towards using css as the main
interface handle, add and update such accessors to ease dealing with
css's.

All accessors explicitly handle NULL input and return NULL in those
cases.  While this looks like an extra branch in the code, as all
controllers specific data structures have css as the first field, the
casting doesn't involve any offsetting and the compiler can trivially
optimize out the branch.

* blkio, freezer, cpuset, cpu, cpuacct and net_cls didn't have such
  accessor.  Added.

* memory, hugetlb and devices already had one but didn't explicitly
  handle NULL input.  Updated.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-08 20:11:23 -04:00
Tejun Heo
8af01f56a0 cgroup: s/cgroup_subsys_state/cgroup_css/ s/task_subsys_state/task_css/
The names of the two struct cgroup_subsys_state accessors -
cgroup_subsys_state() and task_subsys_state() - are somewhat awkward.
The former clashes with the type name and the latter doesn't even
indicate it's somehow related to cgroup.

We're about to revamp large portion of cgroup API, so, let's rename
them so that they're less awkward.  Most per-controller usages of the
accessors are localized in accessor wrappers and given the amount of
scheduled changes, this isn't gonna add any noticeable headache.

Rename cgroup_subsys_state() to cgroup_css() and task_subsys_state()
to task_css().  This patch is pure rename.

Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Li Zefan <lizefan@huawei.com>
2013-08-08 20:11:22 -04:00
Dave Kleikamp
10e84b97ed mm: sched: numa: fix NUMA balancing when !SCHED_DEBUG
Commit 3105b86a9f ("mm: sched: numa: Control enabling and disabling of
NUMA balancing if !SCHED_DEBUG") defined numabalancing_enabled to
control the enabling and disabling of automatic NUMA balancing, but it
is never used.

I believe the intention was to use this in place of sched_feat_numa(NUMA).

Currently, if SCHED_DEBUG is not defined, sched_feat_numa(NUMA) will
never be changed from the initial "false".

Signed-off-by: Dave Kleikamp <dave.kleikamp@oracle.com>
Acked-by: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2013-07-31 14:41:02 -07:00
Peter Zijlstra
bf0bd948d1 sched: Ensure update_cfs_shares() is called for parents of continuously-running tasks
We typically update a task_group's shares within the dequeue/enqueue
path.  However, continuously running tasks sharing a CPU are not
subject to these updates as they are only put/picked.  Unfortunately,
when we reverted f269ae046 (in 17bc14b7), we lost the augmenting
periodic update that was supposed to account for this; resulting in a
potential loss of fairness.

To fix this, re-introduce the explicit update in
update_cfs_rq_blocked_load() [called via entity_tick()].

Reported-by: Max Hailperin <max@gustavus.edu>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Reviewed-by: Paul Turner <pjt@google.com>
Link: http://lkml.kernel.org/n/tip-9545m3apw5d93ubyrotrj31y@git.kernel.org
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-07-30 22:14:37 +02:00
Peter Zijlstra
7d9ffa8961 sched: Micro-optimize the smart wake-affine logic
Smart wake-affine is using node-size as the factor currently, but the overhead
of the mask operation is high.

Thus, this patch introduce the 'sd_llc_size' percpu variable, which will record
the highest cache-share domain size, and make it to be the new factor, in order
to reduce the overhead and make it more reasonable.

Tested-by: Davidlohr Bueso <davidlohr.bueso@hp.com>
Tested-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Michael Wang <wangyun@linux.vnet.ibm.com>
Cc: Mike Galbraith <efault@gmx.de>
Link: http://lkml.kernel.org/r/51D5008E.6030102@linux.vnet.ibm.com
[ Tidied up the changelog. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2013-07-23 12:22:06 +02:00