From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Christoph Lameter <cl@gentwo.org>
Cc: Andi Kleen <ak@linux.intel.com>,
Dave Hansen <dave.hansen@intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Josh Triplett <josh@joshtriplett.org>,
"Chen, Tim C" <tim.c.chen@intel.com>
Subject: Re: [bisected] pre-3.16 regression on open() scalability
Date: Thu, 19 Jun 2014 11:09:16 -0700 [thread overview]
Message-ID: <20140619180916.GE4904@linux.vnet.ibm.com> (raw)
In-Reply-To: <alpine.DEB.2.11.1406190941180.2785@gentwo.org>
On Thu, Jun 19, 2014 at 09:42:18AM -0500, Christoph Lameter wrote:
> On Wed, 18 Jun 2014, Andi Kleen wrote:
>
> > I still think it's totally the wrong direction to pollute so
> > many fast paths with this obscure debugging check workaround
> > unconditionally.
> >
> > cond_resched() is in EVERY sleeping lock and in EVERY memory allocation!
> > And these are really critical paths for many workloads.
> >
> > If you really wanted to do this I think you would first need
> > to define a cond_resched_i_am_not_fast() or somesuch.
> >
> > Or put it all behind some debugging ifdef.
>
> Again I am fully on Andi's side here. Please remove these frequent calls
> to cond_resched. If one wants a fully preemptable kernel then please use
> CONFIG_PREEMPT.
That is a separate issue, but unnecessary calls to cond_resched()
should of course be removed -- no argument there.
Thanx, Paul
next prev parent reply other threads:[~2014-06-19 18:09 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-13 20:04 [bisected] pre-3.16 regression on open() scalability Dave Hansen
2014-06-13 22:45 ` Paul E. McKenney
2014-06-13 23:35 ` Dave Hansen
2014-06-14 2:03 ` Paul E. McKenney
2014-06-17 23:10 ` Dave Hansen
2014-06-18 0:00 ` Josh Triplett
2014-06-18 0:15 ` Andi Kleen
2014-06-18 1:04 ` Paul E. McKenney
2014-06-18 2:27 ` Andi Kleen
2014-06-18 4:47 ` Paul E. McKenney
2014-06-18 12:40 ` Andi Kleen
2014-06-18 12:56 ` Paul E. McKenney
2014-06-18 14:29 ` Christoph Lameter
2014-06-18 0:18 ` Paul E. McKenney
2014-06-18 6:33 ` Dave Hansen
2014-06-18 12:58 ` Paul E. McKenney
2014-06-18 17:36 ` Dave Hansen
2014-06-18 20:30 ` Paul E. McKenney
2014-06-18 23:51 ` Paul E. McKenney
2014-06-19 1:42 ` Andi Kleen
2014-06-19 2:13 ` Paul E. McKenney
2014-06-19 2:29 ` Paul E. McKenney
2014-06-19 2:50 ` Mike Galbraith
2014-06-19 4:19 ` Paul E. McKenney
2014-06-19 3:38 ` Andi Kleen
2014-06-19 4:19 ` Paul E. McKenney
2014-06-19 5:24 ` Mike Galbraith
2014-06-19 18:14 ` Paul E. McKenney
2014-06-19 4:52 ` Eric Dumazet
2014-06-19 5:23 ` Paul E. McKenney
2014-06-19 14:42 ` Christoph Lameter
2014-06-19 18:09 ` Paul E. McKenney [this message]
2014-06-19 20:31 ` Christoph Lameter
2014-06-19 20:42 ` Paul E. McKenney
2014-06-19 20:50 ` Andi Kleen
2014-06-19 21:03 ` Paul E. McKenney
2014-06-19 21:13 ` Christoph Lameter
2014-06-19 21:16 ` Christoph Lameter
2014-06-19 21:32 ` josh
2014-06-19 23:07 ` Paul E. McKenney
2014-06-20 15:20 ` Christoph Lameter
2014-06-20 15:38 ` Paul E. McKenney
2014-06-20 16:07 ` Christoph Lameter
2014-06-20 16:30 ` Paul E. McKenney
2014-06-20 17:39 ` Dave Hansen
2014-06-20 18:15 ` Paul E. McKenney
2014-06-18 21:48 ` Paul E. McKenney
2014-06-18 22:03 ` Dave Hansen
2014-06-18 22:52 ` Paul E. McKenney
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