From: peterz@infradead.org (Peter Zijlstra)
To: linux-arm-kernel@lists.infradead.org
Subject: [BUG] 2.6.37-rc3 massive interactivity regression on ARM
Date: Fri, 10 Dec 2010 11:08:24 +0100 [thread overview]
Message-ID: <1291975704.6803.59.camel@twins> (raw)
In-Reply-To: <AANLkTi=_qf8NAgj2HHMP0qG-ibnH-726NzoXbxd-bS1N@mail.gmail.com>
On Thu, 2010-12-09 at 15:35 -0800, Venkatesh Pallipadi wrote:
>
> Just to make sure, update_rq_clock() always gets called on current
> CPU. Right?
No, specifically not. If that were the case we wouldn't need the
cross-cpu synced timestamp. Things like load-balancing and
remote-wakeups need to update a remote CPUs clock.
> The pending patches I have optimizes
> account_system_vtime() to use this_cpu_write and friends. Want to make
> sure this change will still keep that optimization relevant.
Ah, good point, remote CPUs updating that will mess with the consistency
of the per-cpu timestamps due to non atomic updates :/
Bugger.. making them atomics will make it even more expensive. /me goes
ponder.
WARNING: multiple messages have this Message-ID (diff)
From: Peter Zijlstra <peterz@infradead.org>
To: Venkatesh Pallipadi <venki@google.com>
Cc: Russell King - ARM Linux <linux@arm.linux.org.uk>,
Mikael Pettersson <mikpe@it.uu.se>, Ingo Molnar <mingo@elte.hu>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
John Stultz <johnstul@us.ibm.com>
Subject: Re: [BUG] 2.6.37-rc3 massive interactivity regression on ARM
Date: Fri, 10 Dec 2010 11:08:24 +0100 [thread overview]
Message-ID: <1291975704.6803.59.camel@twins> (raw)
In-Reply-To: <AANLkTi=_qf8NAgj2HHMP0qG-ibnH-726NzoXbxd-bS1N@mail.gmail.com>
On Thu, 2010-12-09 at 15:35 -0800, Venkatesh Pallipadi wrote:
>
> Just to make sure, update_rq_clock() always gets called on current
> CPU. Right?
No, specifically not. If that were the case we wouldn't need the
cross-cpu synced timestamp. Things like load-balancing and
remote-wakeups need to update a remote CPUs clock.
> The pending patches I have optimizes
> account_system_vtime() to use this_cpu_write and friends. Want to make
> sure this change will still keep that optimization relevant.
Ah, good point, remote CPUs updating that will mess with the consistency
of the per-cpu timestamps due to non atomic updates :/
Bugger.. making them atomics will make it even more expensive. /me goes
ponder.
next prev parent reply other threads:[~2010-12-10 10:08 UTC|newest]
Thread overview: 102+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-11-27 15:16 [BUG] 2.6.37-rc3 massive interactivity regression on ARM Mikael Pettersson
2010-11-27 15:16 ` Mikael Pettersson
2010-12-05 12:32 ` Mikael Pettersson
2010-12-05 12:32 ` Mikael Pettersson
2010-12-05 13:17 ` Russell King - ARM Linux
2010-12-05 13:17 ` Russell King - ARM Linux
2010-12-05 14:19 ` Russell King - ARM Linux
2010-12-05 14:19 ` Russell King - ARM Linux
2010-12-05 16:07 ` Mikael Pettersson
2010-12-05 16:07 ` Mikael Pettersson
2010-12-05 16:21 ` Russell King - ARM Linux
2010-12-05 16:21 ` Russell King - ARM Linux
2010-12-08 12:40 ` Peter Zijlstra
2010-12-08 12:40 ` Peter Zijlstra
2010-12-08 12:55 ` Russell King - ARM Linux
2010-12-08 12:55 ` Russell King - ARM Linux
2010-12-08 14:04 ` Peter Zijlstra
2010-12-08 14:04 ` Peter Zijlstra
2010-12-08 14:28 ` Russell King - ARM Linux
2010-12-08 14:28 ` Russell King - ARM Linux
2010-12-08 14:44 ` Peter Zijlstra
2010-12-08 14:44 ` Peter Zijlstra
2010-12-08 15:05 ` Russell King - ARM Linux
2010-12-08 15:05 ` Russell King - ARM Linux
2010-12-08 15:43 ` Linus Walleij
2010-12-08 15:43 ` Linus Walleij
2010-12-08 20:42 ` john stultz
2010-12-08 20:42 ` john stultz
2010-12-08 23:31 ` Venkatesh Pallipadi
2010-12-08 23:31 ` Venkatesh Pallipadi
2010-12-09 12:52 ` Peter Zijlstra
2010-12-09 12:52 ` Peter Zijlstra
2010-12-09 17:43 ` Venkatesh Pallipadi
2010-12-09 17:43 ` Venkatesh Pallipadi
2010-12-09 17:55 ` Peter Zijlstra
2010-12-09 17:55 ` Peter Zijlstra
2010-12-09 18:11 ` Venkatesh Pallipadi
2010-12-09 18:11 ` Venkatesh Pallipadi
2010-12-09 18:55 ` Peter Zijlstra
2010-12-09 18:55 ` Peter Zijlstra
2010-12-09 22:21 ` Venkatesh Pallipadi
2010-12-09 22:21 ` Venkatesh Pallipadi
2010-12-09 23:16 ` Peter Zijlstra
2010-12-09 23:16 ` Peter Zijlstra
2010-12-09 23:35 ` Venkatesh Pallipadi
2010-12-09 23:35 ` Venkatesh Pallipadi
2010-12-10 10:08 ` Peter Zijlstra [this message]
2010-12-10 10:08 ` Peter Zijlstra
2010-12-10 13:17 ` Peter Zijlstra
2010-12-10 13:17 ` Peter Zijlstra
2010-12-10 13:27 ` Peter Zijlstra
2010-12-10 13:27 ` Peter Zijlstra
2010-12-10 13:47 ` Peter Zijlstra
2010-12-10 13:47 ` Peter Zijlstra
2010-12-10 16:50 ` Russell King - ARM Linux
2010-12-10 16:50 ` Russell King - ARM Linux
2010-12-10 16:54 ` Peter Zijlstra
2010-12-10 16:54 ` Peter Zijlstra
2010-12-10 17:18 ` Eric Dumazet
2010-12-10 17:18 ` Eric Dumazet
2010-12-10 17:49 ` Peter Zijlstra
2010-12-10 17:49 ` Peter Zijlstra
2010-12-10 18:14 ` Eric Dumazet
2010-12-10 18:14 ` Eric Dumazet
2010-12-10 18:39 ` Christoph Lameter
2010-12-10 18:39 ` Christoph Lameter
2010-12-10 18:46 ` Peter Zijlstra
2010-12-10 18:46 ` Peter Zijlstra
2010-12-10 19:51 ` Christoph Lameter
2010-12-10 19:51 ` Christoph Lameter
2010-12-10 20:07 ` Peter Zijlstra
2010-12-10 20:07 ` Peter Zijlstra
2010-12-10 20:23 ` Christoph Lameter
2010-12-10 20:23 ` Christoph Lameter
2010-12-10 20:32 ` Peter Zijlstra
2010-12-10 20:32 ` Peter Zijlstra
2010-12-10 20:39 ` Eric Dumazet
2010-12-10 20:39 ` Eric Dumazet
2010-12-10 20:49 ` Eric Dumazet
2010-12-10 20:49 ` Eric Dumazet
2010-12-10 21:09 ` Christoph Lameter
2010-12-10 21:09 ` Christoph Lameter
2010-12-10 21:22 ` Eric Dumazet
2010-12-10 21:22 ` Eric Dumazet
2010-12-10 21:45 ` Christoph Lameter
2010-12-10 21:45 ` Christoph Lameter
2010-12-10 17:56 ` Russell King - ARM Linux
2010-12-10 17:56 ` Russell King - ARM Linux
2010-12-10 18:10 ` Peter Zijlstra
2010-12-10 18:10 ` Peter Zijlstra
2010-12-10 18:43 ` Peter Zijlstra
2010-12-10 18:43 ` Peter Zijlstra
2010-12-10 19:17 ` Russell King - ARM Linux
2010-12-10 19:17 ` Russell King - ARM Linux
2010-12-10 19:37 ` Peter Zijlstra
2010-12-10 19:37 ` Peter Zijlstra
2010-12-10 19:25 ` Peter Zijlstra
2010-12-10 19:25 ` Peter Zijlstra
2010-12-13 14:33 ` Jack Daniel
2010-12-13 14:33 ` Jack Daniel
2010-12-06 21:29 ` Venkatesh Pallipadi
2010-12-06 21:29 ` Venkatesh Pallipadi
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