linux-kernel - Re: SCHED_IDLE documentation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 3 Mar 2008 10:24:22 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Michael Kerrisk <mtk.manpages@...glemail.com>
Cc:	Arnd Bergmann <arnd@...db.de>, Christoph Hellwig <hch@....de>,
	cbe-oss-dev@...abs.org, Jeremy Kerr <jk@...abs.org>,
	linux-kernel@...r.kernel.org
Subject: Re: SCHED_IDLE documentation


* Michael Kerrisk <mtk.manpages@...glemail.com> wrote:

> On Mon, Mar 3, 2008 at 8:33 AM, Ingo Molnar <mingo@...e.hu> wrote:
> >
> > * Arnd Bergmann <arnd@...db.de> wrote:
> >
> > > If we don't have any man page, what is the actual definition of
> > > SCHED_IDLE anyway?
> >
> > it's rather simple: "it's a priority level even lower priority than nice
> > +19".
> 
> Some other questions whose answers may be worth including in the man page:
> 
> * When was SCHED_IDLE added?  (Actually, who added it?)

"git-blame include/linux/sched.h" gives you that information, it was 
added by me as part of CFS:

  commit 0e6aca43e08a62a48d6770e9a159dbec167bf4c6
  Author: Ingo Molnar <mingo@...e.hu>
  Date:   Mon Jul 9 18:51:57 2007 +0200

      sched: add SCHED_IDLE policy
 
> * Why was it added?  (What are the particular benefits of the new 
> sceuling class as opposed to using a very low nice value for 
> SCHED_OTHER?)

because some people wanted even lower priorities than what nice +19 
gave, and extending nice levels wasnt possible for ABI reasons.

> * 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.

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

	Ingo
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/