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| author | Suresh Siddha <suresh.b.siddha@intel.com> | 2010-08-20 02:03:38 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-08-20 14:59:02 +0200 |
| commit | cd7240c0b900eb6d690ccee088a6c9b46dae815a (patch) | |
| tree | 0a1ed10298a2bb2c9d6010c4d03a7f9508bdcba6 /arch/x86/power | |
| parent | sched: Fix rq->clock synchronization when migrating tasks (diff) | |
| download | linux-cd7240c0b900eb6d690ccee088a6c9b46dae815a.tar.xz linux-cd7240c0b900eb6d690ccee088a6c9b46dae815a.zip | |
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/power')
| -rw-r--r-- | arch/x86/power/cpu.c | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/x86/power/cpu.c b/arch/x86/power/cpu.c index e7e8c5f54956..87bb35e34ef1 100644 --- a/arch/x86/power/cpu.c +++ b/arch/x86/power/cpu.c @@ -113,6 +113,7 @@ static void __save_processor_state(struct saved_context *ctxt) void save_processor_state(void) { __save_processor_state(&saved_context); + save_sched_clock_state(); } #ifdef CONFIG_X86_32 EXPORT_SYMBOL(save_processor_state); @@ -229,6 +230,7 @@ static void __restore_processor_state(struct saved_context *ctxt) void restore_processor_state(void) { __restore_processor_state(&saved_context); + restore_sched_clock_state(); } #ifdef CONFIG_X86_32 EXPORT_SYMBOL(restore_processor_state); |