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 1/3] lockdep:reintroduce generation count to make BFS faster
Date: Wed, 22 Jul 2009 21:17:56 +0800 [thread overview]
Message-ID: <d82e647a0907220617p5055ef3bu7f396eda3ac27fa@mail.gmail.com> (raw)
In-Reply-To: <1248267898.27058.1407.camel@twins>
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>
>>
>> We still can apply DaveM's generation count optimization to
>> BFS, so reintroduce it.
>
> Please elaborate, changelogs are important.
Sorry, I'll resend the patches and provide a elaborate changlogs.
>
> You fail to explain why it still applies and what the gains are.
>
> (I can guess, but you explaining makes sure we're on the same page)
>
gains:
1), avoid to allocate the bfs_accessed array;
2), remove the
bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);
in each BFS, which is a little time consuming since
MAX_LOCKDEP_ENTRIES
is very large.(16384UL)
--
Lei Ming
prev parent reply other threads:[~2009-07-22 13:17 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
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 [this message]
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