From: Andy Lutomirski <luto@MIT.EDU>
Date: Mon, 23 May 2011 13:31:27 +0000 (-0400)
Subject: x86-64: Vclock_gettime(CLOCK_MONOTONIC) can't ever see nsec < 0
X-Git-Tag: v3.0-rc1~128^2~5
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0f51f2852ccf0fe38a02d340d0ba625e8e32a863;p=pandora-kernel.git

x86-64: Vclock_gettime(CLOCK_MONOTONIC) can't ever see nsec < 0

vclock_gettime's do_monotonic helper can't ever generate a negative
nsec value, so it doesn't need to check whether it's negative.  In
the CLOCK_MONOTONIC_COARSE case, ns can't ever exceed 2e9-1, so we
can avoid the loop entirely.  This saves a single easily-predicted
branch.

Signed-off-by: Andy Lutomirski <luto@mit.edu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Borislav Petkov <bp@amd64.org>
Link: http://lkml.kernel.org/r/%3Cd6d528d32c7a21618057cfc9005942a0fe5cb54a.1306156808.git.luto%40mit.edu%3E
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---

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