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

[<gregkh@linuxfoundation.org>]

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 <stable@vger.kernel.org>.

thanks,

greg k-h

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

>From f8e617f4582995f7c25ef25b4167213120ad122b Mon Sep 17 00:00:00 2001
From: Mike Galbraith <bitbucket@online.de>
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.

Signed-off-by: Mike Galbraith <bitbucket@online.de>
Cc: <stable@vger.kernel.org> # 3.10+
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>

diff --git a/arch/x86/kernel/process.c b/arch/x86/kernel/process.c
index da06f741d2a6..6ad8a6396b75 100644
--- a/arch/x86/kernel/process.c
+++ b/arch/x86/kernel/process.c
@@ -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)