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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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f685ceacab
This patch restores the effectiveness of LAST_BUDDY in preventing pgsql+oltp from collapsing due to wakeup preemption. It also switches LAST_BUDDY to exclusively do what it does best, namely mitigate the effects of aggressive wakeup preemption, which improves vmark throughput markedly, and restores mysql+oltp scalability. Since buddies are about scalability, enable them beginning at the point where we begin expanding sched_latency, namely sched_nr_latency. Previously, buddies were cleared aggressively, which seriously reduced their effectiveness. Not clearing aggressively however, produces a small drop in mysql+oltp throughput immediately after peak, indicating that LAST_BUDDY is actually doing some harm. This is right at the point where X on the desktop in competition with another load wants low latency service. Ergo, do not enable until we need to scale. To mitigate latency induced by buddies, or by a task just missing wakeup preemption, check latency at tick time. Last hunk prevents buddies from stymieing BALANCE_NEWIDLE via CACHE_HOT_BUDDY. Supporting performance tests: tip = v2.6.32-rc5-1497-ga525b32 tipx = NO_GENTLE_FAIR_SLEEPERS NEXT_BUDDY granularity knobs = 31 knobs + 31 buddies tip+x = NO_GENTLE_FAIR_SLEEPERS granularity knobs = 31 knobs (Three run averages except where noted.) vmark: ------ tip 108466 messages per second tip+ 125307 messages per second tip+x 125335 messages per second tipx 117781 messages per second 2.6.31.3 122729 messages per second mysql+oltp: ----------- clients 1 2 4 8 16 32 64 128 256 .......................................................................................... tip 9949.89 18690.20 34801.24 34460.04 32682.88 30765.97 28305.27 25059.64 19548.08 tip+ 10013.90 18526.84 34900.38 34420.14 33069.83 32083.40 30578.30 28010.71 25605.47 tipx 9698.71 18002.70 34477.56 33420.01 32634.30 31657.27 29932.67 26827.52 21487.18 2.6.31.3 8243.11 18784.20 34404.83 33148.38 31900.32 31161.90 29663.81 25995.94 18058.86 pgsql+oltp: ----------- clients 1 2 4 8 16 32 64 128 256 .......................................................................................... tip 13686.37 26609.25 51934.28 51347.81 49479.51 45312.65 36691.91 26851.57 24145.35 tip+ (1x) 13907.85 27135.87 52951.98 52514.04 51742.52 50705.43 49947.97 48374.19 46227.94 tip+x 13906.78 27065.81 52951.19 52542.59 52176.11 51815.94 50838.90 49439.46 46891.00 tipx 13742.46 26769.81 52351.99 51891.73 51320.79 50938.98 50248.65 48908.70 46553.84 2.6.31.3 13815.35 26906.46 52683.34 52061.31 51937.10 51376.80 50474.28 49394.47 47003.25 Signed-off-by: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> LKML-Reference: <new-submission> Signed-off-by: Ingo Molnar <mingo@elte.hu> |
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.. | ||
gcov | ||
irq | ||
power | ||
time | ||
trace | ||
.gitignore | ||
acct.c | ||
async.c | ||
audit.c | ||
audit.h | ||
audit_tree.c | ||
audit_watch.c | ||
auditfilter.c | ||
auditsc.c | ||
backtracetest.c | ||
bounds.c | ||
capability.c | ||
cgroup.c | ||
cgroup_freezer.c | ||
compat.c | ||
configs.c | ||
cpu.c | ||
cpuset.c | ||
cred-internals.h | ||
cred.c | ||
delayacct.c | ||
dma.c | ||
exec_domain.c | ||
exit.c | ||
extable.c | ||
fork.c | ||
freezer.c | ||
futex.c | ||
futex_compat.c | ||
groups.c | ||
hrtimer.c | ||
hung_task.c | ||
itimer.c | ||
kallsyms.c | ||
Kconfig.freezer | ||
Kconfig.hz | ||
Kconfig.preempt | ||
kexec.c | ||
kfifo.c | ||
kgdb.c | ||
kmod.c | ||
kprobes.c | ||
ksysfs.c | ||
kthread.c | ||
latencytop.c | ||
lockdep.c | ||
lockdep_internals.h | ||
lockdep_proc.c | ||
lockdep_states.h | ||
Makefile | ||
module.c | ||
mutex-debug.c | ||
mutex-debug.h | ||
mutex.c | ||
mutex.h | ||
notifier.c | ||
ns_cgroup.c | ||
nsproxy.c | ||
panic.c | ||
params.c | ||
perf_event.c | ||
pid.c | ||
pid_namespace.c | ||
pm_qos_params.c | ||
posix-cpu-timers.c | ||
posix-timers.c | ||
printk.c | ||
profile.c | ||
ptrace.c | ||
rcupdate.c | ||
rcutorture.c | ||
rcutree.c | ||
rcutree.h | ||
rcutree_plugin.h | ||
rcutree_trace.c | ||
relay.c | ||
res_counter.c | ||
resource.c | ||
rtmutex-debug.c | ||
rtmutex-debug.h | ||
rtmutex-tester.c | ||
rtmutex.c | ||
rtmutex.h | ||
rtmutex_common.h | ||
rwsem.c | ||
sched.c | ||
sched_clock.c | ||
sched_cpupri.c | ||
sched_cpupri.h | ||
sched_debug.c | ||
sched_fair.c | ||
sched_features.h | ||
sched_idletask.c | ||
sched_rt.c | ||
sched_stats.h | ||
seccomp.c | ||
semaphore.c | ||
signal.c | ||
slow-work.c | ||
smp.c | ||
softirq.c | ||
softlockup.c | ||
spinlock.c | ||
srcu.c | ||
stacktrace.c | ||
stop_machine.c | ||
sys.c | ||
sys_ni.c | ||
sysctl.c | ||
sysctl_check.c | ||
taskstats.c | ||
test_kprobes.c | ||
time.c | ||
timeconst.pl | ||
timer.c | ||
tracepoint.c | ||
tsacct.c | ||
uid16.c | ||
up.c | ||
user.c | ||
user_namespace.c | ||
utsname.c | ||
utsname_sysctl.c | ||
wait.c | ||
workqueue.c |