netdev - Re: [PATCH v6] net: batch skb dequeueing from softnet input_pkt

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Message-ID: <20100503103426.GA25809@one.firstfloor.org>
Date:	Mon, 3 May 2010 12:34:26 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Arjan van de Ven <arjan@...radead.org>
Cc:	Eric Dumazet <eric.dumazet@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	David Miller <davem@...emloft.net>, hadi@...erus.ca,
	xiaosuo@...il.com, therbert@...gle.com, shemminger@...tta.com,
	netdev@...r.kernel.org, lenb@...nel.org
Subject: Re: [PATCH v6] net: batch skb dequeueing from softnet input_pkt_queue

> > Maybe its low cost, (apparently, it is, since I can reach ~900.000
> > ipis on my 16 cores machine) but multiply this by 16 or 32 or 64
> > cpus, and clockevents_notify() cost appears to be a killer, all cpus
> > compete on a single lock.
> > 
> > Maybe this notifier could use RCU ?
> 
> could this be an artifact of the local apic stopping in deeper C states?
> (which is finally fixed in the Westmere generation)

Yes it is I think.

But I suspect Eric wants a solution for Nehalem.

-Andi
-- 
ak@...ux.intel.com -- Speaking for myself only.
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