From: David Miller <davem@davemloft.net>
To: dada1@cosmosbay.com
Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org,
a.p.zijlstra@chello.nl
Subject: Re: [PATCH] percpu_counter: Fix __percpu_counter_sum()
Date: Wed, 03 Dec 2008 22:14:36 -0800 (PST) [thread overview]
Message-ID: <20081203.221436.57914253.davem@davemloft.net> (raw)
In-Reply-To: <4936EB04.8000609@cosmosbay.com>
From: Eric Dumazet <dada1@cosmosbay.com>
Date: Wed, 03 Dec 2008 21:24:36 +0100
> [PATCH] percpu_counter: Fix __percpu_counter_sum()
>
> This function should not write into percpu local storage,
> without proper locking, or some changes done on other cpus
> might be lost.
>
> Adding proper locking would need to use atomic
> operations in fast path and would be expensive.
>
> Results of __percpu_counter_sum() can be wrong, this is a
> known fact.
>
> We also dont need to acquire the lock, this gives
> no better results.
>
> Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: David S. Miller <davem@davemloft.net>
next prev parent reply other threads:[~2008-12-04 6:14 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-12-03 18:40 [PATCH] percpu_counter: fix CPU unplug race in percpu_counter_destroy() Eric Dumazet
2008-12-03 20:24 ` [PATCH] percpu_counter: Fix __percpu_counter_sum() Eric Dumazet
2008-12-03 20:45 ` Peter Zijlstra
2008-12-04 6:14 ` David Miller [this message]
2008-12-07 4:22 ` Andrew Morton
2008-12-07 10:25 ` Peter Zijlstra
2008-12-07 13:28 ` Eric Dumazet
2008-12-07 17:28 ` Andrew Morton
2008-12-07 18:00 ` Eric Dumazet
2008-12-08 4:52 ` Andrew Morton
2008-12-08 22:12 ` Theodore Tso
2008-12-08 22:20 ` Peter Zijlstra
2008-12-08 23:00 ` Theodore Tso
2008-12-08 23:05 ` Peter Zijlstra
2008-12-08 23:08 ` Peter Zijlstra
2008-12-09 8:12 ` Eric Dumazet
2008-12-09 8:34 ` Peter Zijlstra
2008-12-10 5:09 ` Eric Dumazet
2008-12-10 5:49 ` Andrew Morton
2008-12-10 22:56 ` Eric Dumazet
2008-12-12 8:17 ` Rusty Russell
2008-12-12 8:22 ` Eric Dumazet
2008-12-12 11:08 ` [PATCH] percpu_counter: use local_t and atomic_long_t if possible Eric Dumazet
2008-12-12 11:29 ` Peter Zijlstra
2008-12-23 11:43 ` Peter Zijlstra
2008-12-25 13:26 ` Rusty Russell
2008-12-15 12:53 ` [PATCH] percpu_counter: Fix __percpu_counter_sum() Rusty Russell
2008-12-16 20:16 ` Ingo Molnar
2008-12-10 7:12 ` Peter Zijlstra
2008-12-08 23:07 ` Andrew Morton
2008-12-08 23:49 ` Theodore Tso
2008-12-08 22:22 ` Andrew Morton
2008-12-08 22:44 ` Mingming Cao
2008-12-07 22:24 ` [PATCH] atomic: fix a typo in atomic_long_xchg() Eric Dumazet
2008-12-07 15:28 ` [PATCH] percpu_counter: Fix __percpu_counter_sum() Theodore Tso
2008-12-08 4:42 ` Andrew Morton
2008-12-08 17:55 ` Mingming Cao
2008-12-11 16:32 ` [stable] " Greg KH
2008-12-08 17:44 ` Mingming Cao
2008-12-04 6:13 ` [PATCH] percpu_counter: fix CPU unplug race in percpu_counter_destroy() David Miller
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