FAILED: patch "[PATCH] sched/idle/x86: Optimize unnecessary mwait_idle() resched" failed to apply to 3.10-stable tree

The patch below does not apply to the 3.10-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From: Mike Galbraith <[email protected]>
Date: Sat, 18 Jan 2014 17:14:44 +0100
Subject: [PATCH] sched/idle/x86: Optimize unnecessary mwait_idle() resched
IPIs

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.

index da06f741d2a6..6ad8a6396b75 100644
@@ -428,18 +428,22 @@ 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)