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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 2/4] net: Percpufy frequently used variables -- struct proto.memory_allocated
Date: Fri, 27 Jan 2006 10:01:15 +0100	[thread overview]
Message-ID: <43D9E15B.9000407@cosmosbay.com> (raw)
In-Reply-To: <20060126190212.GD3651@localhost.localdomain>

Ravikiran G Thirumalai a écrit :
> Change struct proto->memory_allocated to a batching per-CPU counter 
> (percpu_counter) from an atomic_t.  A batching counter is better than a 
> plain per-CPU counter as this field is read often.
> 
> 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>
> 

Hello Ravikiran

I like this patch, but I'm not sure current percpu_counter fits the needs.

The percpu_counter_read() can return a value that is off by +-
FBC_BATCH*NR_CPUS, ie 2*(NR_CPUS^2) or 4*(NR_CPUS^2)

if NR_CPUS = 128, the 'error' from percpu_counter_read() is +- 32768

Is it acceptable ?

Thank you
Eric

  reply	other threads:[~2006-01-27  9:01 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 [this message]
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
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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