From: Con Kolivas <kernel@kolivas.org>
To: Andrew Morton <akpm@osdl.org>
Cc: Ingo Molnar <mingo@elte.hu>, Nick Piggin <piggin@cyberone.com.au>,
linux kernel mailing list <linux-kernel@vger.kernel.org>
Subject: Likelihood of rt_tasks
Date: Fri, 09 Jul 2004 20:00:34 +1000 [thread overview]
Message-ID: <40EE6CC2.8070001@kolivas.org> (raw)
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A quick question about the usefulness of making rt_task() checks
unlikely in sched-unlikely-rt_task.patch which is in -mm
quote:
diff -puN include/linux/sched.h~sched-unlikely-rt_task include/linux/sched.h
--- 25/include/linux/sched.h~sched-unlikely-rt_task Fri Jul 2 16:33:01 2004
+++ 25-akpm/include/linux/sched.h Fri Jul 2 16:33:01 2004
@@ -300,7 +300,7 @@ struct signal_struct {
#define MAX_PRIO (MAX_RT_PRIO + 40)
-#define rt_task(p) ((p)->prio < MAX_RT_PRIO)
+#define rt_task(p) (unlikely((p)->prio < MAX_RT_PRIO))
/*
* Some day this will be a full-fledged user tracking system..
---
While rt tasks are normally unlikely, what happens in the case when you
are scheduling one or many running rt_tasks and the majority of your
scheduling is rt? Would it be such a good idea in this setting that it
is always hitting the slow path of branching all the time?
Con
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next reply other threads:[~2004-07-09 10:04 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-09 10:00 Con Kolivas [this message]
2004-07-09 10:17 ` Likelihood of rt_tasks Ingo Molnar
2004-07-09 23:53 ` Peter Williams
2004-07-10 0:16 ` Con Kolivas
2004-07-10 0:41 ` Peter Williams
2004-07-10 0:45 ` Con Kolivas
2004-07-10 11:15 ` Ingo Molnar
2004-07-10 12:05 ` Nick Piggin
2004-07-10 3:57 ` Elladan
2004-07-10 11:19 ` Ingo Molnar
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