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| author | Suresh Siddha <suresh.b.siddha@intel.com> | 2010-08-20 04:03:38 +0400 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-08-20 16:59:02 +0400 |
| commit | cd7240c0b900eb6d690ccee088a6c9b46dae815a (patch) | |
| tree | 0a1ed10298a2bb2c9d6010c4d03a7f9508bdcba6 /arch/x86/include/asm/tsc.h | |
| parent | 861d034ee814917a83bd5de4b26e3b8336ddeeb8 (diff) | |
| download | linux-cd7240c0b900eb6d690ccee088a6c9b46dae815a.tar.xz | |
x86, tsc, sched: Recompute cyc2ns_offset's during resume from sleep states
TSC's get reset after suspend/resume (even on cpu's with invariant TSC
which runs at a constant rate across ACPI P-, C- and T-states). And in
some systems BIOS seem to reinit TSC to arbitrary large value (still
sync'd across cpu's) during resume.
This leads to a scenario of scheduler rq->clock (sched_clock_cpu()) less
than rq->age_stamp (introduced in 2.6.32). This leads to a big value
returned by scale_rt_power() and the resulting big group power set by the
update_group_power() is causing improper load balancing between busy and
idle cpu's after suspend/resume.
This resulted in multi-threaded workloads (like kernel-compilation) go
slower after suspend/resume cycle on core i5 laptops.
Fix this by recomputing cyc2ns_offset's during resume, so that
sched_clock() continues from the point where it was left off during
suspend.
Reported-by: Florian Pritz <flo@xssn.at>
Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: <stable@kernel.org> # [v2.6.32+]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1282262618.2675.24.camel@sbsiddha-MOBL3.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'arch/x86/include/asm/tsc.h')
| -rw-r--r-- | arch/x86/include/asm/tsc.h | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h index c0427295e8f5..1ca132fc0d03 100644 --- a/arch/x86/include/asm/tsc.h +++ b/arch/x86/include/asm/tsc.h @@ -59,5 +59,7 @@ extern void check_tsc_sync_source(int cpu); extern void check_tsc_sync_target(void); extern int notsc_setup(char *); +extern void save_sched_clock_state(void); +extern void restore_sched_clock_state(void); #endif /* _ASM_X86_TSC_H */ |