public inbox for linux-kernel@vger.kernel.org
 help / color / mirror / Atom feed
From: Tim Blechmann <tim@klingt.org>
To: linux-kernel@vger.kernel.org, x86@kernel.org
Subject: [PATCH] sched, x86: Optimize branch hint in __switch_to()
Date: Sun, 29 Nov 2009 12:55:16 +0100	[thread overview]
Message-ID: <4B126124.60902@klingt.org> (raw)


[-- Attachment #1.1: Type: text/plain, Size: 315 bytes --]


Branch hint profiling on my nehalem machine showed 89%
incorrect branch hints:

31032542 270070841  89 __switch_to                    process_64.c         440

Signed-off-by: Tim Blechmann <tim@klingt.org>
---
 arch/x86/kernel/process_64.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)



[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1.2: 0001-sched-x86-Optimize-branch-hint-in-__switch_to.patch --]
[-- Type: text/x-patch; name="0001-sched-x86-Optimize-branch-hint-in-__switch_to.patch", Size: 591 bytes --]

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index c8d0ece..88068b3 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -437,7 +437,7 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
 	 * reload when it has changed.  When prev process used 64bit
 	 * base always reload to avoid an information leak.
 	 */
-	if (unlikely(fsindex | next->fsindex | prev->fs)) {
+	if (fsindex | next->fsindex | prev->fs) {
 		loadsegment(fs, next->fsindex);
 		/*
 		 * Check if the user used a selector != 0; if yes


[-- Attachment #2: OpenPGP digital signature --]
[-- Type: application/pgp-signature, Size: 197 bytes --]

                 reply	other threads:[~2009-11-29 11:55 UTC|newest]

Thread overview: [no followups] expand[flat|nested]  mbox.gz  Atom feed

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=4B126124.60902@klingt.org \
    --to=tim@klingt.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=x86@kernel.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox