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x86, suspend: Avoid unnecessary smp alternatives switch during suspend/resume

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During suspend, we disable all the non boot cpus. And during resume we bring
them all back again. So no need to do alternatives_smp_switch() in between.

On my core 2 based laptop, this speeds up the suspend path by 15msec and the
resume path by 5 msec (suspend/resume speed up differences can be attributed
to the different P-states that the cpu is in during suspend/resume).

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
LKML-Reference: <1290557500.4946.8.camel@sbsiddha-MOBL3.sc.intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
This commit is contained in:
Suresh Siddha
2010-11-23 16:11:40 -08:00
committed by H. Peter Anvin
parent cf7d7e5a19
commit 3fb82d56ad
4 changed files with 28 additions and 1 deletions
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3
arch/x86/kernel/alternative.c
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@@ -353,6 +353,7 @@ void __init_or_module alternatives_smp_module_del(struct module *mod)
mutex_unlock(&smp_alt);
}
bool skip_smp_alternatives;
void alternatives_smp_switch(int smp)
{
struct smp_alt_module *mod;
@@ -368,7 +369,7 @@ void alternatives_smp_switch(int smp)
printk("lockdep: fixing up alternatives.\n");
#endif
if (noreplace_smp || smp_alt_once)
if (noreplace_smp || smp_alt_once || skip_smp_alternatives)
return;
BUG_ON(!smp && (num_online_cpus() > 1));