From: Thomas Gleixner <tglx@linutronix.de>
Date: Tue, 16 Jun 2009 22:33:39 +0000 (-0700)
Subject: remove put_cpu_no_resched()
X-Git-Tag: v2.6.31-rc1~299^2~67
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8b0b1db0133e4218a9b45c09e53793c039edebe1;p=pandora-kernel.git

remove put_cpu_no_resched()

put_cpu_no_resched() is an optimization of put_cpu() which unfortunately
can cause high latencies.

The nfs iostats code uses put_cpu_no_resched() in a code sequence where a
reschedule request caused by an interrupt between the get_cpu() and the
put_cpu_no_resched() can delay the reschedule for at least HZ.

The other users of put_cpu_no_resched() optimize correctly in interrupt
code, but there is no real harm in using the put_cpu() function which is
an alias for preempt_enable().  The extra check of the preemmpt count is
not as critical as the potential source of missing a reschedule.

Debugged in the preempt-rt tree and verified in mainline.

Impact: remove a high latency source

[akpm@linux-foundation.org: build fix]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>
Cc: "J. Bruce Fields" <bfields@fieldses.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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