From: Arjan van de Ven <arjan@infradead.org>
To: Andi Kleen <andi@firstfloor.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
David Miller <davem@davemloft.net>,
hadi@cyberus.ca, xiaosuo@gmail.com, therbert@google.com,
shemminger@vyatta.com, netdev@vger.kernel.org, lenb@kernel.org
Subject: Re: [PATCH v6] net: batch skb dequeueing from softnet input_pkt_queue
Date: Mon, 3 May 2010 07:09:25 -0700 [thread overview]
Message-ID: <20100503070925.572bbee6@infradead.org> (raw)
In-Reply-To: <20100503103426.GA25809@one.firstfloor.org>
On Mon, 3 May 2010 12:34:26 +0200
Andi Kleen <andi@firstfloor.org> wrote:
> > > 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.
sure ;-)
so the hard problem is that on going idle, the local timers need to be
funneled to the external HPET. Afaik right now we use one channel of
the hpet, with the result that we have one global lock for this.
HPETs have more than one channel (2 or 3 historically, newer chipsets
iirc have a few more), so in principle we can split this lock at least
a little bit... if we can get to one hpet channel per level 3 cache
domain we'd already make huge progress in terms of cost of the
contention....
--
Arjan van de Ven Intel Open Source Technology Centre
For development, discussion and tips for power savings,
visit http://www.lesswatts.org
next prev parent reply other threads:[~2010-05-03 14:07 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-23 8:12 [PATCH v6] net: batch skb dequeueing from softnet input_pkt_queue Changli Gao
2010-04-23 9:27 ` Eric Dumazet
2010-04-23 22:02 ` jamal
2010-04-24 14:10 ` jamal
2010-04-26 14:03 ` Eric Dumazet
2010-04-26 14:55 ` Eric Dumazet
2010-04-26 21:06 ` jamal
[not found] ` <20100429174056.GA8044@gargoyle.fritz.box>
2010-04-29 17:56 ` Eric Dumazet
2010-04-29 18:10 ` OFT - reserving CPU's for networking Stephen Hemminger
2010-04-29 19:19 ` Thomas Gleixner
2010-04-29 20:02 ` Eric Dumazet
2010-04-30 18:15 ` Brian Bloniarz
2010-04-30 18:57 ` David Miller
2010-04-30 19:58 ` Thomas Gleixner
2010-04-30 21:01 ` Andi Kleen
2010-04-30 22:30 ` David Miller
2010-05-01 10:53 ` Andi Kleen
2010-05-01 22:03 ` David Miller
2010-05-01 22:58 ` Andi Kleen
2010-05-01 23:29 ` David Miller
2010-05-01 23:44 ` Ben Hutchings
2010-05-01 20:31 ` Martin Josefsson
2010-05-01 22:13 ` David Miller
[not found] ` <20100429182347.GA8512@gargoyle.fritz.box>
2010-04-29 19:12 ` [PATCH v6] net: batch skb dequeueing from softnet input_pkt_queue Eric Dumazet
[not found] ` <20100429214144.GA10663@gargoyle.fritz.box>
2010-04-30 5:25 ` Eric Dumazet
2010-04-30 23:38 ` David Miller
2010-05-01 11:00 ` Andi Kleen
2010-05-02 6:56 ` Eric Dumazet
2010-05-02 9:20 ` Andi Kleen
2010-05-02 10:54 ` Eric Dumazet
2010-05-02 14:13 ` Arjan van de Ven
2010-05-02 14:27 ` Eric Dumazet
2010-05-02 15:32 ` Eric Dumazet
2010-05-02 17:54 ` Arjan van de Ven
2010-05-02 19:22 ` Eric Dumazet
2010-05-02 22:06 ` Andi Kleen
2010-05-03 3:50 ` Arjan van de Ven
2010-05-03 5:17 ` Eric Dumazet
2010-05-03 10:22 ` Arjan van de Ven
2010-05-03 10:34 ` Andi Kleen
2010-05-03 14:09 ` Arjan van de Ven [this message]
2010-05-03 14:45 ` Brian Bloniarz
2010-05-04 1:10 ` Arjan van de Ven
2010-05-03 15:52 ` Andi Kleen
2010-05-04 1:11 ` Arjan van de Ven
2010-05-02 21:30 ` Andi Kleen
2010-05-02 15:46 ` Andi Kleen
2010-05-02 16:35 ` Eric Dumazet
2010-05-02 17:43 ` Arjan van de Ven
2010-05-02 17:47 ` Eric Dumazet
2010-05-02 21:25 ` Andi Kleen
2010-05-02 21:45 ` Eric Dumazet
2010-05-02 21:54 ` Andi Kleen
2010-05-02 22:08 ` Eric Dumazet
2010-05-03 20:15 ` jamal
2010-04-26 21:03 ` jamal
2010-04-23 10:26 ` Eric Dumazet
2010-04-27 22:08 ` David Miller
2010-04-27 22:18 ` [PATCH net-next-2.6] bnx2x: Remove two prefetch() Eric Dumazet
2010-04-27 22:19 ` David Miller
2010-04-28 13:14 ` Eilon Greenstein
2010-04-28 15:44 ` Eliezer Tamir
2010-04-28 16:53 ` David Miller
[not found] ` <w2ue8f3c3211004280842r9f2589e8qb8fd4b7933cd9756@mail.gmail.com>
2010-04-28 16:55 ` David Miller
2010-04-28 11:33 ` jamal
2010-04-28 12:33 ` Eric Dumazet
2010-04-28 12:36 ` jamal
2010-04-28 14:06 ` [PATCH net-next-2.6] net: speedup udp receive path Eric Dumazet
2010-04-28 14:19 ` Eric Dumazet
2010-04-28 14:34 ` Eric Dumazet
2010-04-28 21:36 ` David Miller
2010-04-28 22:22 ` [PATCH net-next-2.6] net: ip_queue_rcv_skb() helper Eric Dumazet
2010-04-28 22:39 ` David Miller
2010-04-28 23:44 ` [PATCH net-next-2.6] net: speedup udp receive path jamal
2010-04-29 0:00 ` jamal
2010-04-29 4:09 ` Eric Dumazet
2010-04-29 11:35 ` jamal
2010-04-29 12:12 ` Changli Gao
2010-04-29 12:45 ` Eric Dumazet
2010-04-29 13:17 ` jamal
2010-04-29 13:21 ` Eric Dumazet
2010-04-29 13:37 ` jamal
2010-04-29 13:49 ` Eric Dumazet
2010-04-29 13:56 ` jamal
2010-04-29 20:36 ` jamal
2010-04-29 21:01 ` [PATCH net-next-2.6] net: sock_def_readable() and friends RCU conversion Eric Dumazet
2010-04-30 13:55 ` Brian Bloniarz
2010-04-30 17:26 ` Eric Dumazet
2010-04-30 23:35 ` David Miller
2010-05-01 4:56 ` Eric Dumazet
2010-05-01 7:02 ` Eric Dumazet
2010-05-01 8:03 ` Eric Dumazet
2010-05-01 22:00 ` David Miller
2010-04-30 19:30 ` [PATCH net-next-2.6] net: speedup udp receive path jamal
2010-04-30 20:40 ` Eric Dumazet
2010-05-01 0:06 ` jamal
2010-05-01 5:57 ` Eric Dumazet
2010-05-01 6:14 ` Eric Dumazet
2010-05-01 10:24 ` Changli Gao
2010-05-01 10:47 ` Eric Dumazet
2010-05-01 11:29 ` jamal
2010-05-01 11:23 ` jamal
2010-05-01 11:42 ` Eric Dumazet
2010-05-01 11:56 ` jamal
2010-05-01 13:22 ` Eric Dumazet
2010-05-01 13:49 ` jamal
2010-05-03 20:10 ` jamal
2010-04-29 23:07 ` Changli Gao
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