From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
David Miller <davem@davemloft.net>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Russell King <rmk@arm.linux.org.uk>,
Paul Mundt <lethal@linux-sh.org>, Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
Tony Luck <tony.luck@intel.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>,
Namhyung Kim <namhyung@gmail.com>,
ak@linux.intel.com, shaohua.li@intel.com, alex.shi@intel.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [GIT PULL] Re: REGRESSION: Performance regressions from switching anon_vma->lock to mutex
Date: Fri, 17 Jun 2011 08:21:23 +1000 [thread overview]
Message-ID: <1308262883.2516.71.camel@pasglop> (raw)
In-Reply-To: <20110616202550.GA16214@elte.hu>
On Thu, 2011-06-16 at 22:25 +0200, Ingo Molnar wrote:
> > Whatever does the boosting will need to have process context and
> > can be subject to delays, so that pretty much needs to be a
> > kthread. But it will context-switch quite rarely, so should not be
> > a problem.
>
> So user-return notifiers ought to be the ideal platform for that,
> right? We don't even have to touch the scheduler: anything that
> schedules will eventually return to user-space, at which point the
> RCU GC magic can run.
>
> And user-return-notifiers can be triggered from IRQs as well.
>
> That allows us to get rid of softirqs altogether and maybe even speed
> the whole thing up and allow it to be isolated better.
I'm a little worried of relying on things returning to userspace.
One could imagine something like a router appliance where userspace is
essentially asleep forever and everything happens in the kernel
(networking via softirq, maybe NFS kernel server, ...)
Cheers,
Ben.
WARNING: multiple messages have this Message-ID (diff)
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Linus Torvalds <torvalds@linux-foundation.org>,
Peter Zijlstra <peterz@infradead.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Hugh Dickins <hughd@google.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
David Miller <davem@davemloft.net>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Russell King <rmk@arm.linux.org.uk>,
Paul Mundt <lethal@linux-sh.org>, Jeff Dike <jdike@addtoit.com>,
Richard Weinberger <richard@nod.at>,
Tony Luck <tony.luck@intel.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Mel Gorman <mel@csn.ul.ie>, Nick Piggin <npiggin@kernel.dk>,
Namhyung Kim <namhyung@gmail.com>,
ak@linux.intel.com, shaohua.li@intel.com, alex.shi@intel.com,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
"Rafael J. Wysocki" <rjw@sisk.pl>
Subject: Re: [GIT PULL] Re: REGRESSION: Performance regressions from switching anon_vma->lock to mutex
Date: Fri, 17 Jun 2011 08:21:23 +1000 [thread overview]
Message-ID: <1308262883.2516.71.camel@pasglop> (raw)
In-Reply-To: <20110616202550.GA16214@elte.hu>
On Thu, 2011-06-16 at 22:25 +0200, Ingo Molnar wrote:
> > Whatever does the boosting will need to have process context and
> > can be subject to delays, so that pretty much needs to be a
> > kthread. But it will context-switch quite rarely, so should not be
> > a problem.
>
> So user-return notifiers ought to be the ideal platform for that,
> right? We don't even have to touch the scheduler: anything that
> schedules will eventually return to user-space, at which point the
> RCU GC magic can run.
>
> And user-return-notifiers can be triggered from IRQs as well.
>
> That allows us to get rid of softirqs altogether and maybe even speed
> the whole thing up and allow it to be isolated better.
I'm a little worried of relying on things returning to userspace.
One could imagine something like a router appliance where userspace is
essentially asleep forever and everything happens in the kernel
(networking via softirq, maybe NFS kernel server, ...)
Cheers,
Ben.
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next prev parent reply other threads:[~2011-06-16 22:24 UTC|newest]
Thread overview: 166+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-06-15 0:29 REGRESSION: Performance regressions from switching anon_vma->lock to mutex Tim Chen
2011-06-15 0:29 ` Tim Chen
2011-06-15 0:36 ` Andi Kleen
2011-06-15 0:36 ` Andi Kleen
2011-06-17 19:07 ` Ingo Molnar
2011-06-17 19:07 ` Ingo Molnar
2011-06-15 1:21 ` Linus Torvalds
2011-06-15 1:21 ` Linus Torvalds
2011-06-15 3:42 ` Linus Torvalds
2011-06-15 1:26 ` Shaohua Li
2011-06-15 1:26 ` Shaohua Li
2011-06-15 11:52 ` Peter Zijlstra
2011-06-15 11:52 ` Peter Zijlstra
2011-06-15 12:49 ` Peter Zijlstra
2011-06-15 12:49 ` Peter Zijlstra
2011-06-15 16:18 ` Andi Kleen
2011-06-15 16:18 ` Andi Kleen
2011-06-15 16:45 ` Peter Zijlstra
2011-06-15 16:45 ` Peter Zijlstra
2011-06-15 16:47 ` Andi Kleen
2011-06-15 16:47 ` Andi Kleen
2011-06-15 18:43 ` Tim Chen
2011-06-15 18:43 ` Tim Chen
2011-06-15 20:32 ` Peter Zijlstra
2011-06-15 20:32 ` Peter Zijlstra
2011-06-15 20:57 ` Andi Kleen
2011-06-15 20:57 ` Andi Kleen
2011-06-15 21:12 ` Tim Chen
2011-06-15 21:12 ` Tim Chen
2011-06-15 21:37 ` Peter Zijlstra
2011-06-15 21:37 ` Peter Zijlstra
2011-06-15 21:51 ` Linus Torvalds
2011-06-15 21:51 ` Linus Torvalds
2011-06-15 22:19 ` Andi Kleen
2011-06-15 22:19 ` Andi Kleen
2011-06-16 0:16 ` Linus Torvalds
2011-06-16 0:16 ` Linus Torvalds
2011-06-16 20:14 ` Andi Kleen
2011-06-16 20:14 ` Andi Kleen
2011-06-16 20:37 ` Linus Torvalds
2011-06-16 20:37 ` Linus Torvalds
2011-06-17 0:24 ` Andi Kleen
2011-06-17 9:13 ` Ingo Molnar
2011-06-17 9:13 ` Ingo Molnar
2011-06-15 22:15 ` Andi Kleen
2011-06-15 22:15 ` Andi Kleen
2011-06-16 1:08 ` Tim Chen
2011-06-16 1:08 ` Tim Chen
2011-06-16 1:50 ` Linus Torvalds
2011-06-16 1:50 ` Linus Torvalds
2011-06-16 20:26 ` Tim Chen
2011-06-16 20:26 ` Tim Chen
2011-06-16 20:47 ` Linus Torvalds
2011-06-16 20:47 ` Linus Torvalds
2011-06-16 21:05 ` Linus Torvalds
2011-06-16 21:05 ` Linus Torvalds
2011-06-16 21:06 ` Linus Torvalds
2011-06-16 21:26 ` Linus Torvalds
2011-06-16 21:26 ` Linus Torvalds
2011-06-17 3:58 ` Linus Torvalds
2011-06-17 11:28 ` Peter Zijlstra
2011-06-17 11:28 ` Peter Zijlstra
2011-06-17 11:54 ` Peter Zijlstra
2011-06-17 11:54 ` Peter Zijlstra
2011-06-17 16:36 ` Linus Torvalds
2011-06-17 16:36 ` Linus Torvalds
2011-06-17 17:41 ` Hugh Dickins
2011-06-17 17:41 ` Hugh Dickins
2011-06-17 17:55 ` Peter Zijlstra
2011-06-17 17:55 ` Peter Zijlstra
2011-06-17 18:01 ` Linus Torvalds
2011-06-17 18:01 ` Linus Torvalds
2011-06-17 18:18 ` Peter Zijlstra
2011-06-17 18:18 ` Peter Zijlstra
2011-06-17 18:32 ` Peter Zijlstra
2011-06-17 18:32 ` Peter Zijlstra
2011-06-17 18:39 ` Linus Torvalds
2011-06-17 18:41 ` Linus Torvalds
2011-06-17 18:41 ` Linus Torvalds
2011-06-17 20:19 ` Tim Chen
2011-06-17 20:19 ` Tim Chen
2011-06-17 22:20 ` Hugh Dickins
2011-06-17 22:20 ` Hugh Dickins
2011-06-18 4:47 ` Linus Torvalds
2011-06-18 4:47 ` Linus Torvalds
2011-06-17 19:53 ` [PATCH] mm, memory-failure: Fix spinlock vs mutex order Peter Zijlstra
2011-06-17 19:53 ` Peter Zijlstra
2011-06-17 20:04 ` Andi Kleen
2011-06-17 20:04 ` Andi Kleen
2011-06-17 16:46 ` REGRESSION: Performance regressions from switching anon_vma->lock to mutex Linus Torvalds
2011-06-17 16:46 ` Linus Torvalds
2011-06-17 17:28 ` Linus Torvalds
2011-06-17 19:40 ` Andi Kleen
2011-06-17 19:40 ` Andi Kleen
2011-06-18 8:08 ` Ingo Molnar
2011-06-18 8:08 ` Ingo Molnar
2011-06-17 18:22 ` Tim Chen
2011-06-17 18:22 ` Tim Chen
2011-06-17 19:05 ` Ray Lee
2011-06-17 19:05 ` Ray Lee
2011-06-16 22:00 ` Andi Kleen
2011-06-16 22:00 ` Andi Kleen
2011-06-15 10:36 ` Peter Zijlstra
2011-06-15 10:36 ` Peter Zijlstra
2011-06-15 10:58 ` Peter Zijlstra
2011-06-15 10:58 ` Peter Zijlstra
2011-06-15 11:41 ` Peter Zijlstra
2011-06-15 11:41 ` Peter Zijlstra
2011-06-15 19:11 ` Linus Torvalds
2011-06-15 19:11 ` Linus Torvalds
2011-06-15 19:24 ` Andrew Morton
2011-06-15 19:24 ` Andrew Morton
2011-06-15 20:16 ` Ingo Molnar
2011-06-15 20:16 ` Ingo Molnar
2011-06-15 20:55 ` Linus Torvalds
2011-06-15 20:55 ` Linus Torvalds
2011-06-15 20:12 ` [GIT PULL] " Ingo Molnar
2011-06-15 20:12 ` Ingo Molnar
2011-06-15 20:29 ` Paul E. McKenney
2011-06-15 20:29 ` Paul E. McKenney
2011-06-15 20:47 ` Linus Torvalds
2011-06-15 20:47 ` Linus Torvalds
2011-06-15 20:54 ` Paul E. McKenney
2011-06-15 20:54 ` Paul E. McKenney
2011-06-15 21:05 ` Linus Torvalds
2011-06-15 21:05 ` Linus Torvalds
2011-06-15 21:15 ` Paul E. McKenney
2011-06-15 21:15 ` Paul E. McKenney
2011-06-15 21:27 ` Linus Torvalds
2011-06-15 21:27 ` Linus Torvalds
2011-06-16 7:03 ` Ingo Molnar
2011-06-16 7:03 ` Ingo Molnar
2011-06-16 17:16 ` Paul E. McKenney
2011-06-16 17:16 ` Paul E. McKenney
2011-06-16 20:25 ` Ingo Molnar
2011-06-16 20:25 ` Ingo Molnar
2011-06-16 21:01 ` Frederic Weisbecker
2011-06-16 21:01 ` Frederic Weisbecker
2011-06-16 23:02 ` Ingo Molnar
2011-06-16 23:02 ` Ingo Molnar
2011-06-17 15:19 ` Frederic Weisbecker
2011-06-17 15:19 ` Frederic Weisbecker
2011-06-16 21:02 ` Andi Kleen
2011-06-16 21:02 ` Andi Kleen
2011-06-16 22:21 ` Benjamin Herrenschmidt [this message]
2011-06-16 22:21 ` Benjamin Herrenschmidt
2011-06-16 22:38 ` Ingo Molnar
2011-06-16 22:38 ` Ingo Molnar
2011-06-16 22:47 ` Andi Kleen
2011-06-16 22:47 ` Andi Kleen
2011-06-16 22:58 ` Ingo Molnar
2011-06-16 22:58 ` Ingo Molnar
2011-06-17 0:45 ` Paul E. McKenney
2011-06-17 0:45 ` Paul E. McKenney
2011-06-17 9:43 ` Ingo Molnar
2011-06-17 9:43 ` Ingo Molnar
2011-06-17 16:48 ` Paul E. McKenney
2011-06-17 16:48 ` Paul E. McKenney
2011-06-16 23:37 ` Paul E. McKenney
2011-06-16 23:37 ` Paul E. McKenney
2011-06-15 20:13 ` Tim Chen
2011-06-15 20:13 ` Tim Chen
2011-06-15 20:17 ` Ingo Molnar
2011-06-15 20:17 ` Ingo Molnar
2011-06-15 20:21 ` Tim Chen
2011-06-15 20:21 ` Tim Chen
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