From: Gustavo Chain <g@0xff.cl>
To: Al Boldi <a1426z@gawab.com>
Cc: LKML Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] Reserve N process to root
Date: Fri, 12 Oct 2007 21:34:36 -0400 [thread overview]
Message-ID: <20071012213436.0b53fa23@0xff.cl> (raw)
In-Reply-To: <200710120929.10770.a1426z@gawab.com>
El Fri, 12 Oct 2007 09:29:10 +0300
Al Boldi <a1426z@gawab.com> escribió:
> Kyle Moffett wrote:
> > On Oct 12, 2007, at 01:37:23, Al Boldi wrote:
> > > You have a point, and resource-controllers can probably control
> > > DoS a lot better, but the they also incur more overhead. Think
> > > of this "lockout prevention" patch as a near zero overhead safety
> > > valve.
> >
> > But why do you need to add "lockout prevention" if it already
> > exists?
>
> I said this before, but I'll say it again: it's about overhead!
>
> > With CFS' extremely efficient per-user-scheduling (hopefully
> > soon to be the default) there are only two forms of lockout by non-
> > root processes: (1) Running out of PIDs in the box's PID-space
> > (think tens or hundreds of thousands of processes), or (2) Swap-
> > storming the box to death. To put it bluntly trying to reserve free
> > PID slots is attacking the wrong end of the problem and your so
> > called "lockout prevention" could very easily ensure that 10 PIDs
> > are available even if the user has swapstormed the box with the
> > PIDs he does have.
>
> I think you are reading this wrong. It's not about reserving PIDs,
> it's about exceeding the max-threads limit. This limit is global and
> affects every user including root, which is good, as this allows the
> sysadmin to fence the system into a controllable state. So once the
> system reaches the fence, sysadmin-intervention allows root to exceed
> the fence.
>
> Again, this is much nicer with real resource-controllers, but again
> it's also more overhead.
Just an _if()_ ?
may be enable it as an option in kernel config ?
>
> Thanks!
>
> --
> Al
>
> -
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--
Gustavo Chaín Dumit
Alumno de Ingeniería de Ejecución Informática
Pontificia Universidad Católica de Valparaiso
http://aleph.homeunix.com/~gchain
next prev parent reply other threads:[~2007-10-13 1:35 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-11 21:02 [PATCH] Reserve N process to root Al Boldi
2007-10-12 2:42 ` Kyle Moffett
2007-10-12 5:37 ` Al Boldi
2007-10-12 5:49 ` Kyle Moffett
2007-10-12 6:29 ` Al Boldi
2007-10-13 1:34 ` Gustavo Chain [this message]
2007-10-13 5:01 ` Al Boldi
-- strict thread matches above, loose matches on Subject: below --
2007-10-09 23:48 Gustavo Chain
2007-10-10 1:49 ` David Newall
2007-10-10 5:15 ` Gustavo Chain
2007-10-10 5:44 ` David Newall
2007-10-10 13:46 ` Gustavo Chain
2007-10-10 14:13 ` David Newall
2007-10-10 19:50 ` Valdis.Kletnieks
2007-10-10 21:02 ` g
2007-10-11 0:05 ` David Newall
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