linux-kernel - Re: CFS review

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]

Message-Id: <1186113467.3996.0.camel@laptopd505.fenrus.org>
Date:	Thu, 02 Aug 2007 20:57:47 -0700
From:	Arjan van de Ven <arjan@...radead.org>
To:	Matt Mackall <mpm@...enic.com>
Cc:	Ingo Molnar <mingo@...e.hu>, Roman Zippel <zippel@...ux-m68k.org>,
	Mike Galbraith <efault@....de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org
Subject: Re: CFS review

On Thu, 2007-08-02 at 22:04 -0500, Matt Mackall wrote:
> On Wed, Aug 01, 2007 at 01:22:29PM +0200, Ingo Molnar wrote:
> > 
> > * Roman Zippel <zippel@...ux-m68k.org> wrote:
> > 
> > > [...] e.g. in this example there are three tasks that run only for 
> > > about 1ms every 3ms, but they get far more time than should have 
> > > gotten fairly:
> > > 
> > >  4544 roman     20   0  1796  520  432 S 32.1  0.4   0:21.08 lt
> > >  4545 roman     20   0  1796  344  256 R 32.1  0.3   0:21.07 lt
> > >  4546 roman     20   0  1796  344  256 R 31.7  0.3   0:21.07 lt
> > >  4547 roman     20   0  1532  272  216 R  3.3  0.2   0:01.94 l
> > 
> > Mike and me have managed to reproduce similarly looking 'top' output, 
> > but it takes some effort: we had to deliberately run a non-TSC 
> > sched_clock(), CONFIG_HZ=100, !CONFIG_NO_HZ and !CONFIG_HIGH_RES_TIMERS.
> 
> ..which is pretty much the state of play for lots of non-x86 hardware.

question is if it's significantly worse than before. With a 100 or
1000Hz timer, you can't expect perfect fairness just due to the
extremely rough measurement of time spent...


-
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/