summaryrefslogtreecommitdiff
path: root/arch
diff options
context:
space:
mode:
authorMike Galbraith <bitbucket@online.de>2014-01-18 17:14:44 +0100
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2015-05-06 22:03:37 +0200
commitaaa51337c5819599af0d1f6aba6a31639dd1c0a6 (patch)
treea447b1fbc6dbe16c224235967c1da686fa8c06d3 /arch
parent0e625b6df5ac57968c7ab197e916ea03f70e4a24 (diff)
sched/idle/x86: Optimize unnecessary mwait_idle() resched IPIs
commit f8e617f4582995f7c25ef25b4167213120ad122b upstream. To fully take advantage of MWAIT, apparently the CLFLUSH instruction needs another quirk on certain CPUs: proper barriers around it on certain machines. On a Q6600 SMP system, pipe-test scheduling performance, cross core, improves significantly: 3.8.13 487.2 KHz 1.000 3.13.0-master 415.5 KHz .852 3.13.0-master+ 415.2 KHz .852 + restore mwait_idle 3.13.0-master++ 488.5 KHz 1.002 + restore mwait_idle + IPI fix Since X86_BUG_CLFLUSH_MONITOR is already a quirk, don't create a separate quirk for the extra smp_mb()s. Signed-off-by: Mike Galbraith <bitbucket@online.de> Cc: Borislav Petkov <bp@alien8.de> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Ian Malone <ibmalone@gmail.com> Cc: Josh Boyer <jwboyer@redhat.com> Cc: Len Brown <len.brown@intel.com> Cc: Len Brown <lenb@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/1390061684.5566.4.camel@marge.simpson.net [ Ported to recent kernel, added comments about the quirk. ] Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/process.c12
1 files changed, 8 insertions, 4 deletions
diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index 65e1a9075d09..a388bb883128 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -429,18 +429,22 @@ static int prefer_mwait_c1_over_halt(const struct cpuinfo_x86 *c)
static void mwait_idle(void)
{
- if (!need_resched()) {
- if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR))
+ if (!current_set_polling_and_test()) {
+ if (this_cpu_has(X86_BUG_CLFLUSH_MONITOR)) {
+ smp_mb(); /* quirk */
clflush((void *)&current_thread_info()->flags);
+ smp_mb(); /* quirk */
+ }
__monitor((void *)&current_thread_info()->flags, 0, 0);
- smp_mb();
if (!need_resched())
__sti_mwait(0, 0);
else
local_irq_enable();
- } else
+ } else {
local_irq_enable();
+ }
+ __current_clr_polling();
}
void select_idle_routine(const struct cpuinfo_x86 *c)