From: Eric Dumazet <dada1@cosmosbay.com>
To: Ravikiran G Thirumalai <kiran@scalex86.org>
Cc: Andrew Morton <akpm@osdl.org>,
davem@davemloft.net, linux-kernel@vger.kernel.org,
shai@scalex86.org, netdev@vger.kernel.org,
pravins@calsoftinc.com
Subject: Re: [patch 3/4] net: Percpufy frequently used variables -- proto.sockets_allocated
Date: Fri, 27 Jan 2006 09:53:53 +0100 [thread overview]
Message-ID: <43D9DFA1.9070802@cosmosbay.com> (raw)
In-Reply-To: <20060126190357.GE3651@localhost.localdomain>
Ravikiran G Thirumalai a écrit :
> Change the atomic_t sockets_allocated member of struct proto to a
> per-cpu counter.
>
> Signed-off-by: Pravin B. Shelar <pravins@calsoftinc.com>
> Signed-off-by: Ravikiran Thirumalai <kiran@scalex86.org>
> Signed-off-by: Shai Fultheim <shai@scalex86.org>
>
Hi Ravikiran
If I correctly read this patch, I think there is a scalability problem.
On a big SMP machine, read_sockets_allocated() is going to be a real killer.
Say we have 128 Opterons CPUS in a box.
You'll need to bring 128 cache lines (plus 8*128 bytes to read the 128
pointers inside percpu structure)
I think a solution 'a la percpu_counter' is preferable, or even better a
dedicated per_cpu with a threshold management (see mm/swap.c , function
vm_acct_memory() to see how vm_committed_space is updated without too bad SMP
scalability)
Thank you
Eric
next prev parent reply other threads:[~2006-01-27 8:54 UTC|newest]
Thread overview: 39+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-01-26 18:56 [patch 0/4] net: Percpufy frequently used variables on struct proto Ravikiran G Thirumalai
2006-01-26 18:59 ` [patch 1/4] net: Percpufy frequently used variables -- add percpu_counter_mod_bh Ravikiran G Thirumalai
2006-01-26 19:02 ` [patch 2/4] net: Percpufy frequently used variables -- struct proto.memory_allocated Ravikiran G Thirumalai
2006-01-27 9:01 ` Eric Dumazet
2006-01-26 19:03 ` [patch 3/4] net: Percpufy frequently used variables -- proto.sockets_allocated Ravikiran G Thirumalai
2006-01-27 8:53 ` Eric Dumazet [this message]
2006-01-27 19:52 ` Ravikiran G Thirumalai
2006-01-27 20:16 ` Andrew Morton
2006-01-27 22:30 ` Eric Dumazet
2006-01-27 22:50 ` Ravikiran G Thirumalai
2006-01-27 23:21 ` Eric Dumazet
2006-01-28 0:40 ` Ravikiran G Thirumalai
2006-01-27 22:44 ` Ravikiran G Thirumalai
2006-01-27 22:58 ` Eric Dumazet
2006-01-27 23:16 ` Andrew Morton
2006-01-28 0:28 ` Eric Dumazet
2006-01-28 0:35 ` Eric Dumazet
2006-01-28 4:52 ` Ravikiran G Thirumalai
2006-01-28 7:19 ` Eric Dumazet
2006-01-28 0:43 ` Andrew Morton
2006-01-28 1:10 ` Eric Dumazet
2006-01-28 1:18 ` Andrew Morton
2006-01-29 0:44 ` Benjamin LaHaise
2006-01-29 0:55 ` Andrew Morton
2006-01-29 1:19 ` Benjamin LaHaise
2006-01-29 1:29 ` Andrew Morton
2006-01-29 1:45 ` Kyle McMartin
2006-01-29 5:38 ` Andi Kleen
2006-01-29 6:54 ` Eric Dumazet
2006-01-29 19:52 ` Benjamin LaHaise
2006-01-27 23:01 ` Andrew Morton
2006-01-27 23:08 ` Andrew Morton
2006-01-28 0:01 ` Ravikiran G Thirumalai
2006-01-28 0:26 ` Andrew Morton
2006-02-03 3:05 ` Ravikiran G Thirumalai
2006-02-03 3:16 ` Andrew Morton
2006-02-03 19:37 ` Ravikiran G Thirumalai
2006-02-03 20:13 ` Andrew Morton
2006-01-26 19:05 ` [patch 4/4] net: Percpufy frequently used variables -- proto.inuse Ravikiran G Thirumalai
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