From cd7240c0b900eb6d690ccee088a6c9b46dae815a Mon Sep 17 00:00:00 2001 From: Suresh Siddha Date: Thu, 19 Aug 2010 17:03:38 -0700 Subject: 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 Signed-off-by: Suresh Siddha Cc: # [v2.6.32+] Signed-off-by: Peter Zijlstra LKML-Reference: <1282262618.2675.24.camel@sbsiddha-MOBL3.sc.intel.com> Signed-off-by: Ingo Molnar --- arch/x86/include/asm/tsc.h | 2 ++ 1 file changed, 2 insertions(+) (limited to 'arch/x86/include/asm') diff --git a/arch/x86/include/asm/tsc.h b/arch/x86/include/asm/tsc.h index c0427295e8f..1ca132fc0d0 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 */ -- cgit v1.2.3-18-g5258