lkml.org 
[lkml]   [2007]   [Aug]   [21]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [accounting regression since rc1] scheduler updates

* Christian Borntraeger <borntraeger@de.ibm.com> wrote:

> Am Montag, 20. August 2007 schrieb Ingo Molnar:
> > could you send that precise sched_clock() patch? It should be an order
> > of magnitude simpler than the high-precision stime/utime tracking you
> > already do, and it's needed for quality scheduling anyway.
>
> I have a question about that. I just played with sched_clock, and even
> when I intentionally slow down sched_clock by a factor of 2, my cpu
> bound process gets 100 % in top. If this is intentional, I dont
> understand how a virtualized sched_clock would fix the accounting
> change?

hm, does on s390 scheduler_tick() get driven in virtual time or in real
time? The very latest scheduler code will enforce a minimum rate of
sched_clock() across two scheduler_tick() calls (in rc3 and later
kernels). If sched_clock() "slows down" but scheduler_tick() still has a
real-time frequency then that impacts the quality of scheduling. So
scheduler_tick() and sched_clock() must really have the same behavior
(either both are virtual or both are real), so that scheduling becomes
invariant to steal-time.

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

\
 
 \ /
  Last update: 2007-08-21 10:45    [W:0.194 / U:2.048 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site