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From: Eric Dumazet <eric.dumazet@gmail.com>
To: Stephen Hemminger <shemminger@vyatta.com>
Cc: "David S. Miller" <davem@davemloft.net>,
	Linux Netdev List <netdev@vger.kernel.org>
Subject: Re: [PATCH] inet_peer: Optimize inet_getid()
Date: Thu, 24 Sep 2009 21:57:08 +0200	[thread overview]
Message-ID: <4ABBCF14.5070007@gmail.com> (raw)
In-Reply-To: <20090924123020.59a2ee6e@s6510>

Stephen Hemminger a écrit :
> On Thu, 24 Sep 2009 21:04:56 +0200
> Eric Dumazet <eric.dumazet@gmail.com> wrote:
> 
>> While investigating for network latencies, I found inet_getid() was a contention point
>> for some workloads.
>>
>> Fix is straightforward, using cmpxchg() instead of
>> a spin_lock_bh()/spin_unlock_bh() pair on a central lock.
>>
>> Another possibility was to use an atomic_t and atomic_add_return() but
>> the size of struct inet_peer object would had doubled on x86_64 because of
>> SLAB_HWCACHE_ALIGN constraint.
>>
>> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
> 
> I thought cmpxchg was not available on all architectures.

Good point Stephen, I forgot about non x86 arches ;)

I'll send an update with cmpxchg() if available, and atomic_t as fallback.

  reply	other threads:[~2009-09-24 19:57 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-09-24 19:04 [PATCH] inet_peer: Optimize inet_getid() Eric Dumazet
2009-09-24 19:30 ` Stephen Hemminger
2009-09-24 19:57   ` Eric Dumazet [this message]
2009-09-24 20:44   ` Eric Dumazet
2009-10-05  7:08     ` David Miller
2009-10-05  7:38       ` Eric Dumazet

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