From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Ingo Molnar <mingo@elte.hu>, Steven Rostedt <rostedt@goodmis.org>,
Tony Lindgren <tony@atomide.com>, Mike Galbraith <efault@gmx.de>
Subject: Re: [RFC PATCH 00/11] sched: CFS low-latency features
Date: Fri, 27 Aug 2010 11:50:13 -0400 [thread overview]
Message-ID: <20100827155013.GF14926@Krystal> (raw)
In-Reply-To: <alpine.LFD.2.00.1008271033030.2768@localhost.localdomain>
* Thomas Gleixner (tglx@linutronix.de) wrote:
> On Thu, 26 Aug 2010, Mathieu Desnoyers wrote:
[...]
> > Hrm, thinking about it a little more, one of the "plus" sides of these
> > SIGEV_THREAD timers is that a single timer can fork threads that will run on
> > many cores on a multi-core system. If we go for preallocation of a single
> > thread, we lose that. Maybe we could think of a way to preallocate a thread pool
> > instead ?
>
> Why should a single timer fork many threads? Just because a previous
> thread did not complete before the timer fires again? That's
> braindamage as all threads call the same function which then needs to
> be serialized anyway. We really do not need a function which creates
> tons of threads which get all stuck on the same resource.
It could make sense if the workload is mostly CPU-bound and there is only a very
short critical section shared between the threads. But I agree that in many
cases this will generate an utter contention mess.
Thanks,
Mathieu
--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
next prev parent reply other threads:[~2010-08-27 15:50 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-26 18:09 [RFC PATCH 00/11] sched: CFS low-latency features Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 01/11] sched: fix string comparison in features Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 02/11] sched: debug spread check account for nr_running Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 03/11] sched: FAIR_SLEEPERS feature Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 04/11] sched: debug cleanup place entity Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 05/11] sched buddy enable buddy logic starting at 2 running threads Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 06/11] sched: dynamic min_vruntime Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 07/11] sched rename struct task in_iowait field to sched_in_iowait Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 08/11] sched input interactivity-driven next buddy Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 09/11] sched: timer-driven " Mathieu Desnoyers
2010-08-27 18:02 ` [RFC PATCH 09/11] sched: timer-driven next buddy (update) Mathieu Desnoyers
2010-08-27 18:14 ` Thomas Gleixner
2010-08-26 18:09 ` [RFC PATCH 10/11] sched: fork expedited Mathieu Desnoyers
2010-08-26 18:09 ` [RFC PATCH 11/11] sched: fair sleepers for timer and interactive Mathieu Desnoyers
2010-08-26 18:57 ` [RFC PATCH 00/11] sched: CFS low-latency features Peter Zijlstra
2010-08-26 21:25 ` Thomas Gleixner
2010-08-26 22:22 ` Thomas Gleixner
2010-08-26 23:09 ` Mathieu Desnoyers
2010-08-26 23:36 ` Mathieu Desnoyers
2010-08-27 7:38 ` Peter Zijlstra
2010-08-27 15:23 ` Mathieu Desnoyers
2010-08-27 8:43 ` Thomas Gleixner
2010-08-27 15:50 ` Mathieu Desnoyers [this message]
2010-08-27 7:37 ` Peter Zijlstra
2010-08-27 15:21 ` Mathieu Desnoyers
2010-08-27 15:41 ` Peter Zijlstra
2010-08-27 16:09 ` Mathieu Desnoyers
2010-08-27 17:27 ` Peter Zijlstra
2010-08-27 18:32 ` Mathieu Desnoyers
2010-08-27 19:23 ` Peter Zijlstra
2010-08-27 19:57 ` Mathieu Desnoyers
2010-08-31 15:02 ` Mathieu Desnoyers
2010-08-26 23:18 ` Paul E. McKenney
2010-08-26 23:28 ` Mathieu Desnoyers
2010-08-26 23:38 ` Paul E. McKenney
2010-08-26 23:53 ` Mathieu Desnoyers
2010-08-27 0:09 ` Paul E. McKenney
2010-08-27 15:18 ` Mathieu Desnoyers
2010-08-27 15:20 ` Thomas Gleixner
2010-08-27 15:30 ` Mathieu Desnoyers
2010-08-27 15:41 ` Peter Zijlstra
2010-08-26 23:49 ` Mathieu Desnoyers
2010-08-27 7:42 ` Peter Zijlstra
2010-08-27 8:19 ` Mike Galbraith
2010-08-27 15:43 ` Mathieu Desnoyers
2010-08-27 18:38 ` Mathieu Desnoyers
2010-08-28 7:33 ` Mike Galbraith
2010-08-27 10:47 ` Indan Zupancic
2010-08-27 10:58 ` Peter Zijlstra
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=20100827155013.GF14926@Krystal \
--to=mathieu.desnoyers@efficios.com \
--cc=akpm@linux-foundation.org \
--cc=efault@gmx.de \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=peterz@infradead.org \
--cc=rostedt@goodmis.org \
--cc=tglx@linutronix.de \
--cc=tony@atomide.com \
--cc=torvalds@linux-foundation.org \
/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