From: jamal <hadi@cyberus.ca>
To: Andi Kleen <andi@firstfloor.org>
Cc: Changli Gao <xiaosuo@gmail.com>,
Eric Dumazet <eric.dumazet@gmail.com>,
Rick Jones <rick.jones2@hp.com>,
David Miller <davem@davemloft.net>,
therbert@google.com, netdev@vger.kernel.org, robert@herjulf.net
Subject: Re: rps perfomance WAS(Re: rps: question
Date: Fri, 16 Apr 2010 09:27:35 -0400 [thread overview]
Message-ID: <1271424455.4606.39.camel@bigi> (raw)
In-Reply-To: <20100416071522.GY18855@one.firstfloor.org>
On Fri, 2010-04-16 at 09:15 +0200, Andi Kleen wrote:
> > resched IPI, apparently. But it is async absolutely. and its IRQ
> > handler is lighter.
>
> It shouldn't be a lot lighter than the new fancy "queued smp_call_function"
> that's in the tree for a few releases. So it would surprise me if it made
> much difference. In the old days when there was only a single lock for
> s_c_f() perhaps...
So you are saying that the old implementation of IPI (likely what i
tried pre-napi and as recent as 2-3 years ago) was bad because of a
single lock?
BTW, I directed some questions to you earlier but didnt get a response,
to quote:
---
On IPIs:
Is anyone familiar with what is going on with Nehalem? Why is it this
good? I expect things will get a lot nastier with other hardware like
xeon based or even Nehalem with rps going across QPI.
Here's why i think IPIs are bad, please correct me if i am wrong:
- they are synchronous. i.e an IPI issuer has to wait for an ACK (which
is in the form of an IPI).
- data cache has to be synced to main memory
- the instruction pipeline is flushed
- what else did i miss? Andi?
---
Do you know any specs i could read up which will tell me a little more?
cheers,
jamal
next prev parent reply other threads:[~2010-04-16 13:27 UTC|newest]
Thread overview: 86+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-02-07 18:42 rps: question jamal
2010-02-08 5:58 ` Tom Herbert
2010-02-08 15:09 ` jamal
2010-04-14 11:53 ` rps perfomance WAS(Re: " jamal
2010-04-14 17:31 ` Tom Herbert
2010-04-14 18:04 ` Eric Dumazet
2010-04-14 18:53 ` jamal
2010-04-14 19:44 ` Stephen Hemminger
2010-04-14 19:58 ` Eric Dumazet
2010-04-15 8:51 ` David Miller
2010-04-14 20:22 ` jamal
2010-04-14 20:27 ` Eric Dumazet
2010-04-14 20:38 ` jamal
2010-04-14 20:45 ` Tom Herbert
2010-04-14 20:57 ` Eric Dumazet
2010-04-14 22:51 ` Changli Gao
2010-04-14 23:02 ` Stephen Hemminger
2010-04-15 2:40 ` Eric Dumazet
2010-04-15 2:50 ` Changli Gao
2010-04-15 8:57 ` David Miller
2010-04-15 12:10 ` jamal
2010-04-15 12:32 ` Changli Gao
2010-04-15 12:50 ` jamal
2010-04-15 23:51 ` Changli Gao
2010-04-15 8:51 ` David Miller
2010-04-14 20:34 ` Andi Kleen
2010-04-15 8:50 ` David Miller
2010-04-15 8:48 ` David Miller
2010-04-15 11:55 ` jamal
2010-04-15 16:41 ` Rick Jones
2010-04-15 20:16 ` jamal
2010-04-15 20:25 ` Rick Jones
2010-04-15 23:56 ` Changli Gao
2010-04-16 5:18 ` Eric Dumazet
2010-04-16 6:02 ` Changli Gao
2010-04-16 6:28 ` Tom Herbert
2010-04-16 6:32 ` Eric Dumazet
2010-04-16 13:42 ` jamal
2010-04-16 7:15 ` Andi Kleen
2010-04-16 13:27 ` jamal [this message]
2010-04-16 13:37 ` Andi Kleen
2010-04-16 13:58 ` jamal
2010-04-16 13:21 ` jamal
2010-04-16 13:34 ` Changli Gao
2010-04-16 13:49 ` jamal
2010-04-16 14:10 ` Changli Gao
2010-04-16 14:43 ` jamal
2010-04-16 14:58 ` Changli Gao
2010-04-19 12:48 ` jamal
2010-04-17 7:35 ` Eric Dumazet
2010-04-17 8:43 ` Tom Herbert
2010-04-17 9:23 ` Eric Dumazet
2010-04-17 14:27 ` Eric Dumazet
2010-04-17 17:26 ` Tom Herbert
2010-04-17 14:17 ` [PATCH net-next-2.6] net: remove time limit in process_backlog() Eric Dumazet
2010-04-18 9:36 ` David Miller
2010-04-17 17:31 ` rps perfomance WAS(Re: rps: question jamal
2010-04-18 9:39 ` Eric Dumazet
2010-04-18 11:34 ` Eric Dumazet
2010-04-19 2:09 ` jamal
2010-04-19 9:37 ` [RFC] rps: shortcut net_rps_action() Eric Dumazet
2010-04-19 9:48 ` Changli Gao
2010-04-19 12:14 ` Eric Dumazet
2010-04-19 12:28 ` Changli Gao
2010-04-19 13:27 ` Eric Dumazet
2010-04-19 14:22 ` Eric Dumazet
2010-04-19 15:07 ` [PATCH net-next-2.6] " Eric Dumazet
2010-04-19 16:02 ` Tom Herbert
2010-04-19 20:21 ` David Miller
2010-04-20 7:17 ` [PATCH net-next-2.6] rps: cleanups Eric Dumazet
2010-04-20 8:18 ` David Miller
2010-04-19 23:56 ` [PATCH net-next-2.6] rps: shortcut net_rps_action() Changli Gao
2010-04-20 0:32 ` Changli Gao
2010-04-20 5:55 ` Eric Dumazet
2010-04-20 12:02 ` rps perfomance WAS(Re: rps: question jamal
2010-04-20 13:13 ` Eric Dumazet
[not found] ` <1271853570.4032.21.camel@bigi>
2010-04-21 19:01 ` Eric Dumazet
2010-04-22 1:27 ` Changli Gao
2010-04-22 12:12 ` jamal
2010-04-25 2:31 ` Changli Gao
2010-04-26 11:35 ` jamal
2010-04-26 13:35 ` Changli Gao
2010-04-21 21:53 ` Rick Jones
2010-04-16 15:57 ` Tom Herbert
2010-04-14 18:53 ` Stephen Hemminger
2010-04-15 8:42 ` David Miller
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