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From: Ming Lei <tom.leiming@gmail.com>
To: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
	mingo@elte.hu, torvalds@linux-foundation.org
Subject: Re: [tip:core/locking 2/3] lockdep:define preallocated "stack" for  BFS as per cpu variable
Date: Wed, 22 Jul 2009 21:45:02 +0800	[thread overview]
Message-ID: <d82e647a0907220645s109f487fva6d68a9abea68372@mail.gmail.com> (raw)
In-Reply-To: <1248268755.27058.1426.camel@twins>

2009/7/22 Peter Zijlstra <a.p.zijlstra@chello.nl>:
> On Wed, 2009-07-22 at 21:10 +0800, Ming Lei wrote:
>> 2009/7/22 Peter Zijlstra <a.p.zijlstra@chello.nl>:
>> > On Wed, 2009-07-22 at 20:58 +0800, tom.leiming@gmail.com wrote:
>> >> From: Ming Lei <tom.leiming@gmail.com>
>> >
>> > This patch can use a changelog.
>> >
>> > Why is this needed, isn't all that serialized by the graph_lock anyway?
>> > Or are there a few paths where this isn't the case and we're now racy?
>>
>> It is really serialized by the graph_lock, but we can prevent cpu cache from
>> being flushing by different cpu access,  which seems that can be avoided by
>> per cpu variables. Right?
>
> I doubt it'll make a difference, got any numbers to back that up?

OK, I'll design some test case to get the numbers.

Thanks.


-- 
Lei Ming

  reply	other threads:[~2009-07-22 13:45 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-07-22 12:58 [tip:core/locking 0/3] lockdep:bfs optimization tom.leiming
2009-07-22 12:58 ` [tip:core/locking 1/3] lockdep:reintroduce generation count to make BFS faster tom.leiming
2009-07-22 12:58   ` [tip:core/locking 2/3] lockdep:define preallocated "stack" for BFS as per cpu variable tom.leiming
2009-07-22 12:58     ` [tip:core/locking 3/3] lockdep:add likely/unlikely annotations to BFS core routine tom.leiming
2009-07-22 13:06       ` Peter Zijlstra
2009-07-22 13:03     ` [tip:core/locking 2/3] lockdep:define preallocated "stack" for BFS as per cpu variable Peter Zijlstra
2009-07-22 13:10       ` Ming Lei
2009-07-22 13:19         ` Peter Zijlstra
2009-07-22 13:45           ` Ming Lei [this message]
2009-07-22 13:04   ` [tip:core/locking 1/3] lockdep:reintroduce generation count to make BFS faster Peter Zijlstra
2009-07-22 13:17     ` Ming Lei

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