From: Mike Galbraith <efault@gmx.de>
To: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@osdl.org>,
lkml <linux-kernel@vger.kernel.org>,
Peter Williams <pwil3058@bigpond.net.au>,
Nick Piggin <nickpiggin@yahoo.com.au>,
Con Kolivas <kernel@kolivas.org>
Subject: Re: [patch 2.6.16-mm2 8/9] sched throttle tree extract - maximize timeslice accounting
Date: Sat, 01 Apr 2006 11:26:47 +0200 [thread overview]
Message-ID: <1143883607.7617.71.camel@homer> (raw)
In-Reply-To: <1143883385.7617.66.camel@homer>
This patch maximizes time slice accounting. A task which receives too
much CPU time due to missing the timer interrupt will have the excess
deducted from it's next slice.
Signed-off-by: Mike Galbraith <efault@gmx.de>
--- linux-2.6.16-mm2/kernel/sched.c-7.implement_throttle 2006-03-24 09:36:08.000000000 +0100
+++ linux-2.6.16-mm2/kernel/sched.c 2006-03-24 09:40:33.000000000 +0100
@@ -2966,13 +2966,28 @@ static void refresh_timeslice(task_t *p)
unsigned int slice = last_slice(p);
unsigned int slice_avg, cpu, idle;
long run_time = -1 * p->slice_time_ns;
+ long slice_time_ns = task_timeslice_ns(p);
int w = MAX_BONUS, delta, bonus;
/*
- * Update time_slice.
+ * Update time_slice. Account for unused fragment,
+ * or excess time received due to missed tick.
*/
- p->slice_time_ns = task_timeslice_ns(p);
- p->time_slice = task_timeslice(p);
+ p->slice_time_ns += slice_time_ns;
+ /*
+ * Not common, but this does happen on SMP systems.
+ * Timeslice theft of this magnitude has never been
+ * observed in the wild, so assume that this is BS,
+ * and give the poor task it's full slice. Theory:
+ * mostly idle task migrates between CPUs numerous
+ * times during it's slice, timestamp rounding leads
+ * to wildly inaccurate calculation. Rounding has
+ * maximum effect on those who stretch their slice,
+ * but is also fairly meaningless, so ignore it.
+ */
+ if (unlikely(p->slice_time_ns < NS_TICK))
+ p->slice_time_ns = slice_time_ns;
+ p->time_slice = NS_TO_JIFFIES(p->slice_time_ns);
set_last_slice(p, p->time_slice);
/*
next prev parent reply other threads:[~2006-04-01 9:26 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-04-01 8:28 [patch 2.6.16-mm2 0/9] sched throttle tree extract Mike Galbraith
2006-04-01 8:33 ` [patch 2.6.16-mm2 1/9] sched throttle tree extract - ignore invalid timestamps Mike Galbraith
2006-04-01 8:38 ` [patch 2.6.16-mm2 2/9] sched throttle tree extract - fix potential task uninterruptible bug Mike Galbraith
2006-04-01 8:44 ` [patch 2.6.16-mm2 3/9] sched throttle tree extract - remove IO priority barrier Mike Galbraith
2006-04-01 8:51 ` [patch 2.6.16-mm2 4/9] sched throttle tree extract - remove kthread barrier Mike Galbraith
2006-04-01 8:59 ` [patch 2.6.16-mm2 5/9] sched throttle tree extract - correct idle sleep logic Mike Galbraith
2006-04-01 9:12 ` [patch 2.6.16-mm2 6/9] sched throttle tree extract - move division to slow path Mike Galbraith
2006-04-01 9:23 ` [patch 2.6.16-mm2 7/9] sched throttle tree extract - implement throttling Mike Galbraith
2006-04-01 9:26 ` Mike Galbraith [this message]
2006-04-01 9:31 ` [patch 2.6.16-mm2 9/9] sched throttle tree extract - export tunables Mike Galbraith
2006-04-05 17:38 ` [patch 2.6.16-mm2 10/9] sched throttle tree extract - kill interactive task feedback loop Mike Galbraith
2006-04-05 23:15 ` Con Kolivas
2006-04-06 4:10 ` Mike Galbraith
2006-04-06 4:29 ` Con Kolivas
2006-04-01 16:53 ` [patch 2.6.16-mm2 5/9] sched throttle tree extract - correct idle sleep logic Lee Revell
2006-04-01 18:00 ` Mike Galbraith
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1143883607.7617.71.camel@homer \
--to=efault@gmx.de \
--cc=akpm@osdl.org \
--cc=kernel@kolivas.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=nickpiggin@yahoo.com.au \
--cc=pwil3058@bigpond.net.au \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox