From mboxrd@z Thu Jan  1 00:00:00 1970
From: Arjan van de Ven <arjan@infradead.org>
Subject: Re: [PATCH v6] net: batch skb dequeueing from softnet
 input_pkt_queue
Date: Mon, 3 May 2010 03:22:27 -0700
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Cc: Andi Kleen <andi@firstfloor.org>,
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To: Eric Dumazet <eric.dumazet@gmail.com>
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On Mon, 03 May 2010 07:17:14 +0200
Eric Dumazet <eric.dumazet@gmail.com> wrote:

> Le dimanche 02 mai 2010 =C3=A0 20:50 -0700, Arjan van de Ven a =C3=A9=
crit :
>=20
> > we effectively do that. The thing is that C2 is so low cost normall=
y
> > that it's still worth it even at 20k wakeups...
> >=20
> > this is where the bios tells us how "heavy" the states are....
> > and 64 usec... is just not very much.
>=20
> 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.
>=20
> 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)



--=20
Arjan van de Ven 	Intel Open Source Technology Centre
=46or development, discussion and tips for power savings,=20
visit http://www.lesswatts.org