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author | Ingo Molnar <mingo@elte.hu> | 2010-10-07 09:43:11 +0200 |
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committer | Ingo Molnar <mingo@elte.hu> | 2010-10-07 09:43:11 +0200 |
commit | d4f8f217b8a5d5bd02af979650418dca4caec472 (patch) | |
tree | af047bfa9729c975e24cb7624107574e884d3a57 /arch/x86/kernel/tsc.c | |
parent | 2dfbf4dfbe47a484bae20456c12b40763b9b6af7 (diff) | |
parent | 773e3f93577ffb493fb7c39b1a6ecf39b5748e87 (diff) | |
download | kernel_samsung_smdk4412-d4f8f217b8a5d5bd02af979650418dca4caec472.zip kernel_samsung_smdk4412-d4f8f217b8a5d5bd02af979650418dca4caec472.tar.gz kernel_samsung_smdk4412-d4f8f217b8a5d5bd02af979650418dca4caec472.tar.bz2 |
Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/rcu
Diffstat (limited to 'arch/x86/kernel/tsc.c')
-rw-r--r-- | arch/x86/kernel/tsc.c | 38 |
1 files changed, 38 insertions, 0 deletions
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c index ce8e502..d632934 100644 --- a/arch/x86/kernel/tsc.c +++ b/arch/x86/kernel/tsc.c @@ -626,6 +626,44 @@ static void set_cyc2ns_scale(unsigned long cpu_khz, int cpu) local_irq_restore(flags); } +static unsigned long long cyc2ns_suspend; + +void save_sched_clock_state(void) +{ + if (!sched_clock_stable) + return; + + cyc2ns_suspend = sched_clock(); +} + +/* + * Even on processors with invariant TSC, TSC gets reset in some the + * ACPI system sleep states. And in some systems BIOS seem to reinit TSC to + * arbitrary value (still sync'd across cpu's) during resume from such sleep + * states. To cope up with this, recompute the cyc2ns_offset for each cpu so + * that sched_clock() continues from the point where it was left off during + * suspend. + */ +void restore_sched_clock_state(void) +{ + unsigned long long offset; + unsigned long flags; + int cpu; + + if (!sched_clock_stable) + return; + + local_irq_save(flags); + + get_cpu_var(cyc2ns_offset) = 0; + offset = cyc2ns_suspend - sched_clock(); + + for_each_possible_cpu(cpu) + per_cpu(cyc2ns_offset, cpu) = offset; + + local_irq_restore(flags); +} + #ifdef CONFIG_CPU_FREQ /* Frequency scaling support. Adjust the TSC based timer when the cpu frequency |