From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Morton <akpm@osdl.org>
Subject: Re: [patch 2/4] net: percpufy frequently used vars -- struct
 proto.memory_allocated
Date: Tue, 7 Mar 2006 18:14:22 -0800
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Cc: linux-kernel@vger.kernel.org, davem@davemloft.net,
	netdev@vger.kernel.org, shai@scalex86.org
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To: Ravikiran G Thirumalai <kiran@scalex86.org>
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Ravikiran G Thirumalai <kiran@scalex86.org> wrote:
>
> -	if (atomic_read(sk->sk_prot->memory_allocated) < sk->sk_prot->sysctl_mem[0]) {
>  +	if (percpu_counter_read(sk->sk_prot->memory_allocated) <
>  +			sk->sk_prot->sysctl_mem[0]) {

Bear in mind that percpu_counter_read[_positive] can be inaccurate on large
CPU counts.

It might be worth running percpu_counter_sum() to get the exact count if we
think we're about to cause something to fail.