Re: [patch][rfc] quell interactive feeding frenzy

From: Al Boldi <a1426z@gawab.com>
To: Con Kolivas <kernel@kolivas.org>
Cc: ck list <ck@vds.kolivas.org>,
	linux-kernel@vger.kernel.org, Mike Galbraith <efault@gmx.de>
Subject: Re: [patch][rfc] quell interactive feeding frenzy
Date: Sat, 15 Apr 2006 23:45:39 +0300	[thread overview]
Message-ID: <200604152345.39850.a1426z@gawab.com> (raw)
In-Reply-To: <200604151705.18786.kernel@kolivas.org>

Con Kolivas wrote:
> On Friday 14 April 2006 13:16, Al Boldi wrote:
> > Can you try the attached mem-eater passing it the number of kb to be
> > eaten.
> >
> >         i.e. '# while :; do ./eatm 9999 ; done'
> >
> > This will print the number of bytes eaten and the timing in ms.
> >
> > Assuming timeslice=100, adjust the number of kb to be eaten such that
> > the timing will be less than timeslice (something like 60ms).  Switch to
> > another vt and start another eatm w/ the number of kb yielding more than
> > timeslice (something like 140ms).  This eatm should starve completely
> > after exceeding timeslice.
> >
> > This problem also exists in mainline, but it is able to break out of it
> > to some extent.  Setting eatm kb to a timing larger than timeslice does
> > not exhibit this problem.
>
> Thanks for bringing this to my attention. A while back I had different
> management of forked tasks and merged it with PF_NONSLEEP. Since then I've
> changed the management of NONSLEEP tasks and didn't realise it had
> adversely affected the accounting of forking tasks. This patch should
> rectify it.

Congrats!

Much smoother, but I still get this choke w/ 2 eatm 9999 loops running:

9 MB 783 KB eaten in 131 msec (74 MB/s)
9 MB 783 KB eaten in 129 msec (75 MB/s)
9 MB 783 KB eaten in 129 msec (75 MB/s)
9 MB 783 KB eaten in 131 msec (74 MB/s)
9 MB 783 KB eaten in 133 msec (73 MB/s)
9 MB 783 KB eaten in 132 msec (73 MB/s)
9 MB 783 KB eaten in 128 msec (76 MB/s)
9 MB 783 KB eaten in 133 msec (73 MB/s)
9 MB 783 KB eaten in 129 msec (75 MB/s)
9 MB 783 KB eaten in 130 msec (74 MB/s)
9 MB 783 KB eaten in 2416 msec (3 MB/s)		<<<<<<<<<<<<<
9 MB 783 KB eaten in 197 msec (48 MB/s)
9 MB 783 KB eaten in 133 msec (73 MB/s)
9 MB 783 KB eaten in 132 msec (73 MB/s)
9 MB 783 KB eaten in 132 msec (73 MB/s)
9 MB 783 KB eaten in 126 msec (77 MB/s)
9 MB 783 KB eaten in 135 msec (72 MB/s)
9 MB 783 KB eaten in 132 msec (73 MB/s)
9 MB 783 KB eaten in 132 msec (73 MB/s)
9 MB 783 KB eaten in 134 msec (72 MB/s)
9 MB 783 KB eaten in 64 msec (152 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 64 msec (152 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 64 msec (152 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)
9 MB 783 KB eaten in 63 msec (154 MB/s)

You may have to adjust the kb to get the same effect.

Thanks!

--
Al