From: Peter Zijlstra <a.p.zijlstra@chello.nl>
To: Theodore Tso <tytso@mit.edu>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Eric Dumazet <dada1@cosmosbay.com>,
linux kernel <linux-kernel@vger.kernel.org>,
"David S. Miller" <davem@davemloft.net>,
Mingming Cao <cmm@us.ibm.com>,
linux-ext4@vger.kernel.org
Subject: Re: [PATCH] percpu_counter: Fix __percpu_counter_sum()
Date: Tue, 09 Dec 2008 00:05:00 +0100 [thread overview]
Message-ID: <1228777500.12729.4.camel@twins> (raw)
In-Reply-To: <20081208230047.GC2501@mit.edu>
On Mon, 2008-12-08 at 18:00 -0500, Theodore Tso wrote:
> On Mon, Dec 08, 2008 at 11:20:35PM +0100, Peter Zijlstra wrote:
> >
> > atomic_t is pretty good on all archs, but you get to keep the cacheline
> > ping-pong.
> >
>
> Stupid question --- if you're worried about cacheline ping-pongs, why
> aren't each cpu's delta counter cacheline aligned? With a 64-byte
> cache-line, and a 32-bit counters entry, with less than 16 CPU's we're
> going to be getting cache ping-pong effects with percpu_counter's,
> right? Or am I missing something?
sorta - a new per-cpu allocator is in the works, but we do cacheline
align the per-cpu allocations (or used to), also, the allocations are
node affine.
next prev parent reply other threads:[~2008-12-08 23:05 UTC|newest]
Thread overview: 52+ 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
2008-12-07 4:22 ` Andrew Morton
2008-12-07 4:22 ` Andrew Morton
2008-12-07 10:25 ` Peter Zijlstra
2008-12-07 13:28 ` Eric Dumazet
2008-12-07 13:28 ` Eric Dumazet
2008-12-07 17:28 ` Andrew Morton
2008-12-07 18:00 ` Eric Dumazet
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 [this message]
2008-12-08 23:08 ` Peter Zijlstra
2008-12-09 8:12 ` Eric Dumazet
2008-12-09 8:12 ` Eric Dumazet
2008-12-09 8:34 ` Peter Zijlstra
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
2008-12-10 22:56 ` Eric Dumazet
2008-12-12 8:17 ` Rusty Russell
2008-12-12 8:22 ` Eric Dumazet
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 11:08 ` 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
2008-12-08 22:44 ` Mingming Cao
2008-12-07 22:24 ` [PATCH] atomic: fix a typo in atomic_long_xchg() Eric Dumazet
2008-12-07 22:24 ` 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
2008-12-08 17:55 ` Mingming Cao
2008-12-11 16:32 ` [stable] " Greg KH
2008-12-08 17:44 ` Mingming Cao
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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