Re: Interesting interaction between lguest and CFS

From: Ingo Molnar
Date: Mon Jun 04 2007 - 16:24:25 EST



* James Morris <jmorris@xxxxxxxxx> wrote:

> On Mon, 4 Jun 2007, Ingo Molnar wrote:
>
> > perhaps lguest does something unusual when it idles? Does it fiddle
> > sched_clock() in any way?
>
> One of the lguest processes calls nice(2), which seems like a long
> shot, but also not impossibly related. (Note that newer patches in
> the lguest queue remove this, so it'll depend on exactly which patches
> you have applied).

i've got 2.6.22-rc3-mm1's lguest (with a trivial boot-time crash fix in
sched_clock that i ran into). But nice(2) should only cause a gentle,
20% smaller CPU bandwidth to be allocated by CFS to that thread, nothing
more drastic like user-visible delays.

Ingo
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