From: Steven Rostedt <rostedt@goodmis.org>
To: Jens Axboe <axboe@kernel.dk>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
Ingo Molnar <mingo@kernel.org>,
Matthew Wilcox <willy@linux.intel.com>,
Al Viro <viro@zeniv.linux.org.uk>, Ingo Molnar <mingo@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
linux-nvme@lists.infradead.org,
Linux SCSI List <linux-scsi@vger.kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
Peter Zijlstra <a.p.zijlstra@chello.nl>,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: RFC: Allow block drivers to poll for I/O instead of sleeping
Date: Mon, 24 Jun 2013 20:11:02 -0400 [thread overview]
Message-ID: <20130625001102.GA6623@home.goodmis.org> (raw)
In-Reply-To: <20130624071718.GS9422@kernel.dk>
On Mon, Jun 24, 2013 at 09:17:18AM +0200, Jens Axboe wrote:
> On Sun, Jun 23 2013, Linus Torvalds wrote:
> >
> > You could try to do that either *in* the idle thread (which would take
> > the context switch overhead - maybe negating some of the advantages),
> > or alternatively hook into the scheduler idle logic before actually
> > doing the switch.
>
> It can't happen in the idle thread. If you need to take the context
> switch, then you've negated pretty much all of the gain of the polled
> approach.
What about hooking into the idle_balance code? That happens if we are
about to go to idle but before the full schedule switch to the idle
task.
In __schedule(void):
if (unlikely(!rq->nr_running))
idle_balance(cpu, rq);
-- Steve
next prev parent reply other threads:[~2013-06-25 0:11 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-06-20 20:17 Matthew Wilcox
2013-06-23 10:09 ` Ingo Molnar
2013-06-23 18:29 ` Linus Torvalds
2013-06-24 7:17 ` Jens Axboe
2013-06-25 0:11 ` Steven Rostedt [this message]
2013-06-25 3:07 ` Matthew Wilcox
2013-06-25 13:57 ` Steven Rostedt
2013-06-25 14:57 ` Jens Axboe
2013-06-24 8:07 ` Ingo Molnar
2013-06-25 3:18 ` Matthew Wilcox
2013-06-25 7:07 ` Bart Van Assche
2013-06-25 15:00 ` Jens Axboe
2013-06-27 18:10 ` Rik van Riel
2013-06-23 22:14 ` David Ahern
2013-06-24 8:21 ` Ingo Molnar
2013-06-24 7:15 ` Jens Axboe
2013-06-24 8:18 ` Ingo Molnar
2013-06-25 3:01 ` Matthew Wilcox
2013-06-25 14:55 ` Jens Axboe
2013-06-27 18:42 ` Rik van Riel
2013-07-04 1:13 ` Shaohua Li
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