netdev - Re: [RFC] rps: shortcut net_rps

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Message-ID: <k2u412e6f7f1004190248s8ac633beof2475645e799f2ea@mail.gmail.com>
Date:	Mon, 19 Apr 2010 17:48:39 +0800
From:	Changli Gao <xiaosuo@...il.com>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Tom Herbert <therbert@...gle.com>,
	David Miller <davem@...emloft.net>,
	netdev <netdev@...r.kernel.org>
Subject: Re: [RFC] rps: shortcut net_rps_action()

On Mon, Apr 19, 2010 at 5:37 PM, Eric Dumazet <eric.dumazet@...il.com> wrote:
> net_rps_action() is a bit expensive on NR_CPUS=64..4096 kernels, even if
> RPS is not active.
>
> I add a flag to scan cpumask only if at least one IPI was scheduled.
> Even cpumask_weight() might be expensive on some setups, where
> nr_cpumask_bits could be very big (4096 for example)

How about using a array to save the cpu IDs. The number of CPUs, to
which the IPI will be sent, should be small.

-- 
Regards，
Changli Gao(xiaosuo@...il.com)
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