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From: "Michael Kerrisk" <mtk.manpages@googlemail.com>
To: "Ingo Molnar" <mingo@elte.hu>
Cc: "Arnd Bergmann" <arnd@arndb.de>, "Christoph Hellwig" <hch@lst.de>,
	cbe-oss-dev@ozlabs.org, "Jeremy Kerr" <jk@ozlabs.org>,
	linux-kernel@vger.kernel.org
Subject: Re: SCHED_IDLE documentation
Date: Mon, 3 Mar 2008 13:31:54 +0100	[thread overview]
Message-ID: <cfd18e0f0803030431n69df391dw53843d5079d906dd@mail.gmail.com> (raw)
In-Reply-To: <20080303092422.GA18281@elte.hu>

Ingo,

> > * What's the difference between SCHED_IDLE and SCHED_BATCH?
>
> SCHED_BATCH can still have nice levels from -20 to +19, it is a modified
> SCHED_OTHER/SCHED_NORMAL for "throughput oriented" workloads.

So, suppose we have two CPU intensive jobs, one SCHED_OTHER and the
other SCHED_BATCH.  If they have the same nice value, will/should the
scheduler favour one over the other?

I've done some testing on 2.6.25-rc2, x86-32 for this case, and it
appears that the two jobs are treated the same by the scheduler (each
gets 50% of CPU).  Is that expected behavior?  If it is, can you give
an example where scheduling SCHED_OTHER versus SCHED_BATCH should show
a difference in the amount of CPU received by each process?

> SCHED_IDLE overrides the nice settings and it means a "super idle"
> workload.

Tested on 2.6.25-rc2, x86-32.  Two CPU intensive jobs, one
SCHED_OTHER, nice=+19, the other SCHED_IDLE.  The SCHED_OTHER job gets
~88% of CPU.  So SCHED_IDLE does indeed give a "super low nice"
effect.

Cheers,

Michael

-- 
Michael Kerrisk
Maintainer of the Linux man-pages project
http://www.kernel.org/doc/man-pages/
Want to report a man-pages bug?  Look here:
http://www.kernel.org/doc/man-pages/reporting_bugs.html

  parent reply	other threads:[~2008-03-03 12:32 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1203376368.275756.252634247263.1.gpush@pokey>
     [not found] ` <200803030612.28039.arnd@arndb.de>
     [not found]   ` <20080303051719.GA26102@lst.de>
2008-03-03  6:21     ` Arnd Bergmann
2008-03-03  7:33       ` Ingo Molnar
2008-03-03  8:40         ` Michael Kerrisk
2008-03-03  9:24           ` Ingo Molnar
2008-03-03  9:31             ` Arnd Bergmann
2008-03-03 10:03               ` Michael Kerrisk
2008-03-03 10:04               ` Ingo Molnar
2008-03-03 10:12                 ` Michael Kerrisk
2008-03-03 10:07             ` Michael Kerrisk
2008-03-03 10:17               ` Ingo Molnar
2008-03-03 10:20                 ` Michael Kerrisk
2008-03-03 12:31             ` Michael Kerrisk [this message]
2008-03-03 12:52               ` Ingo Molnar
2008-03-03 14:06                 ` Michael Kerrisk
2008-03-04 11:11                   ` Peter Zijlstra
2008-03-05 15:19                     ` Michael Kerrisk
2008-03-03 14:42                 ` Michael Kerrisk
2008-03-05 15:02                   ` Michael Kerrisk

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