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https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
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5c87579e65
Add infrastructure to track "maximum allowable latency" for power saving policies. The reason for adding this infrastructure is that power management in the idle loop needs to make a tradeoff between latency and power savings (deeper power save modes have a longer latency to running code again). The code that today makes this tradeoff just does a rather simple algorithm; however this is not good enough: There are devices and use cases where a lower latency is required than that the higher power saving states provide. An example would be audio playback, but another example is the ipw2100 wireless driver that right now has a very direct and ugly acpi hook to disable some higher power states randomly when it gets certain types of error. The proposed solution is to have an interface where drivers can * announce the maximum latency (in microseconds) that they can deal with * modify this latency * give up their constraint and a function where the code that decides on power saving strategy can query the current global desired maximum. This patch has a user of each side: on the consumer side, ACPI is patched to use this, on the producer side the ipw2100 driver is patched. A generic maximum latency is also registered of 2 timer ticks (more and you lose accurate time tracking after all). While the existing users of the patch are x86 specific, the infrastructure is not. I'd like to ask the arch maintainers of other architectures if the infrastructure is generic enough for their use (assuming the architecture has such a tradeoff as concept at all), and the sound/multimedia driver owners to look at the driver facing API to see if this is something they can use. [akpm@osdl.org: cleanups] Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Acked-by: Jesse Barnes <jesse.barnes@intel.com> Cc: "Brown, Len" <len.brown@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
75 lines
2.8 KiB
Makefile
75 lines
2.8 KiB
Makefile
#
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# Makefile for the linux kernel.
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#
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obj-y = sched.o fork.o exec_domain.o panic.o printk.o profile.o \
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exit.o itimer.o time.o softirq.o resource.o \
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sysctl.o capability.o ptrace.o timer.o user.o \
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signal.o sys.o kmod.o workqueue.o pid.o \
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rcupdate.o extable.o params.o posix-timers.o \
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kthread.o wait.o kfifo.o sys_ni.o posix-cpu-timers.o mutex.o \
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hrtimer.o rwsem.o latency.o
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obj-$(CONFIG_STACKTRACE) += stacktrace.o
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obj-y += time/
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obj-$(CONFIG_DEBUG_MUTEXES) += mutex-debug.o
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obj-$(CONFIG_LOCKDEP) += lockdep.o
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ifeq ($(CONFIG_PROC_FS),y)
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obj-$(CONFIG_LOCKDEP) += lockdep_proc.o
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endif
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obj-$(CONFIG_FUTEX) += futex.o
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ifeq ($(CONFIG_COMPAT),y)
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obj-$(CONFIG_FUTEX) += futex_compat.o
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endif
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obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
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obj-$(CONFIG_DEBUG_RT_MUTEXES) += rtmutex-debug.o
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obj-$(CONFIG_RT_MUTEX_TESTER) += rtmutex-tester.o
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obj-$(CONFIG_GENERIC_ISA_DMA) += dma.o
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obj-$(CONFIG_SMP) += cpu.o spinlock.o
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obj-$(CONFIG_DEBUG_SPINLOCK) += spinlock.o
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obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
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obj-$(CONFIG_UID16) += uid16.o
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obj-$(CONFIG_MODULES) += module.o
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obj-$(CONFIG_KALLSYMS) += kallsyms.o
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obj-$(CONFIG_STACK_UNWIND) += unwind.o
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obj-$(CONFIG_PM) += power/
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obj-$(CONFIG_BSD_PROCESS_ACCT) += acct.o
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obj-$(CONFIG_KEXEC) += kexec.o
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obj-$(CONFIG_COMPAT) += compat.o
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obj-$(CONFIG_CPUSETS) += cpuset.o
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obj-$(CONFIG_IKCONFIG) += configs.o
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obj-$(CONFIG_STOP_MACHINE) += stop_machine.o
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obj-$(CONFIG_AUDIT) += audit.o auditfilter.o
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obj-$(CONFIG_AUDITSYSCALL) += auditsc.o
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obj-$(CONFIG_KPROBES) += kprobes.o
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obj-$(CONFIG_SYSFS) += ksysfs.o
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obj-$(CONFIG_DETECT_SOFTLOCKUP) += softlockup.o
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obj-$(CONFIG_GENERIC_HARDIRQS) += irq/
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obj-$(CONFIG_SECCOMP) += seccomp.o
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obj-$(CONFIG_RCU_TORTURE_TEST) += rcutorture.o
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obj-$(CONFIG_RELAY) += relay.o
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obj-$(CONFIG_TASK_DELAY_ACCT) += delayacct.o
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obj-$(CONFIG_TASKSTATS) += taskstats.o
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ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y)
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# According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is
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# needed for x86 only. Why this used to be enabled for all architectures is beyond
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# me. I suspect most platforms don't need this, but until we know that for sure
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# I turn this off for IA-64 only. Andreas Schwab says it's also needed on m68k
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# to get a correct value for the wait-channel (WCHAN in ps). --davidm
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CFLAGS_sched.o := $(PROFILING) -fno-omit-frame-pointer
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endif
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$(obj)/configs.o: $(obj)/config_data.h
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# config_data.h contains the same information as ikconfig.h but gzipped.
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# Info from config_data can be extracted from /proc/config*
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targets += config_data.gz
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$(obj)/config_data.gz: .config FORCE
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$(call if_changed,gzip)
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quiet_cmd_ikconfiggz = IKCFG $@
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cmd_ikconfiggz = (echo "static const char kernel_config_data[] = MAGIC_START"; cat $< | scripts/bin2c; echo "MAGIC_END;") > $@
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targets += config_data.h
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$(obj)/config_data.h: $(obj)/config_data.gz FORCE
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$(call if_changed,ikconfiggz)
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