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 an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.