From: Steven Rostedt <rostedt@goodmis.org>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@elte.hu>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>
Subject: [RFC][PATCH 06/10] sched: Remove unlikely() from rt_policy() in sched.c
Date: Mon, 06 Dec 2010 20:58:40 -0500 [thread overview]
Message-ID: <20101207021329.792522796@goodmis.org> (raw)
In-Reply-To: 20101207015834.196176991@goodmis.org
[-- Attachment #1: 0006-sched-Remove-unlikely-from-rt_policy-in-sched.c.patch --]
[-- Type: text/plain, Size: 1331 bytes --]
From: Steven Rostedt <srostedt@redhat.com>
The rt_policy() has an unlikely() that the policy it is checking is
of RT priority (SCHED_FIFO or SCHED_RR).
According to the annotate branch profiler it is incorrect most of the time:
correct incorrect % Function File Line
------- --------- - -------- ---- ----
36667 654674 94 rt_policy sched.c 126
This makes sense because the rt_policy() is used by the sched_set_scheduler()
and nice(). Although users may use sys_nice a bit, all RT users use
the sched_set_scheduler() to set their RT priority, including kernel
threads.
The above numbers were from a normal desktop computer running
firefox, evolution, xchat and was part of a distcc compile farm.
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
---
kernel/sched.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/sched.c b/kernel/sched.c
index dc91a4d..269a045 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -123,7 +123,7 @@
static inline int rt_policy(int policy)
{
- if (unlikely(policy == SCHED_FIFO || policy == SCHED_RR))
+ if (policy == SCHED_FIFO || policy == SCHED_RR)
return 1;
return 0;
}
--
1.7.2.3
next prev parent reply other threads:[~2010-12-07 2:13 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-07 1:58 [RFC][PATCH 00/10] incorrect unlikely() and likely() cleanups Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 01/10] sched: Change rt_task(prev) in pre_schedule_rt to likely Steven Rostedt
2010-12-07 3:25 ` Yong Zhang
2010-12-07 3:32 ` Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 02/10] mm: Remove likely() from mapping_unevictable() Steven Rostedt
2010-12-07 2:22 ` Steven Rostedt
2010-12-07 7:02 ` Nick Piggin
2010-12-07 13:06 ` Steven Rostedt
2010-12-07 16:26 ` Rik van Riel
2010-12-10 7:00 ` KOSAKI Motohiro
2010-12-10 7:06 ` Joe Perches
2010-12-10 8:08 ` Miles Bader
2010-12-11 0:09 ` Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 03/10] workqueue: It is likely that WORKER_NOT_RUNNING is true Steven Rostedt
2010-12-07 9:49 ` Tejun Heo
2010-12-07 13:07 ` Steven Rostedt
2010-12-11 0:08 ` Steven Rostedt
2010-12-11 0:09 ` Tejun Heo
2010-12-11 0:12 ` Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 04/10] sched: Change pick_next_task_rt from unlikely to likely Steven Rostedt
2010-12-07 2:46 ` Gregory Haskins
2010-12-07 2:59 ` Steven Rostedt
2010-12-11 0:07 ` Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 05/10] mm: Remove likely() from grab_cache_page_write_begin() Steven Rostedt
2010-12-07 2:24 ` Steven Rostedt
2010-12-07 6:56 ` Nick Piggin
2010-12-07 1:58 ` Steven Rostedt [this message]
2010-12-07 1:58 ` [RFC][PATCH 07/10] x86: Remove unlikey()s from sched_switch segment tests Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 08/10] fs: Remove unlikely() from fput_light() Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 09/10] fs: Remove unlikely() from fget_light() Steven Rostedt
2010-12-07 1:58 ` [RFC][PATCH 10/10] sched: Remove unlikely() from ttwu_post_activation Steven Rostedt
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