LKML Archive on
help / color / mirror / Atom feed
From: Gergely Imre <>
To: Arjan van de Ven <>
Subject: Re: irq balancing question
Date: Fri, 23 Feb 2007 16:58:53 +0200	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

Arjan van de Ven wrote:
> On Fri, 2007-02-23 at 13:32 +0200, Imre Gergely wrote:
>> hi
>> i have a SMP with 2x duo-core Opteron processors, and i have an ethernet card
>> (eth0). i want to balance the interrupts generated by the card to all 4
>> processors. 
> you have only one card? then balancing like you say will only really
> hurt you; neither linux nor the chipset will do this.

in fact i have two cards, and 4 CPUs, but i was interested in then answer
Robert gave, that only _some_ machines distribute interrupts in hardware.
software distribution is obviously not good. consider this scenario:

you have one machine with 4 cpus, and two ethernet cards with a lot of
traffic on them. if you bind every card to one cpu, two of them are not used,
so you really use only half the power. not let's say you have so much traffic
(with limiting enabled, htb or something), that the two CPUs are on 100% all
the time, but the other two are doing nothing.

now if you could balance that to all 4 cpus, you could use all the power AND
no cpu would be used 100%.

but i guess the machine has to do it in hardware, and that was the real
question. irqbalance has no use here, i think, only if the hardware supports it.

is there a way to find out (some easy way) for sure, if one particular
hardware supports this interrupt distribution?

  reply	other threads:[~2007-02-23 14:58 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-02-23 11:32 Imre Gergely
2007-02-23 14:45 ` Arjan van de Ven
2007-02-23 14:58   ` Gergely Imre [this message]
2007-02-23 15:54     ` Arjan van de Ven
2007-02-23 18:51       ` Gergely Imre
2007-02-23 19:01         ` Arjan van de Ven
2007-02-23 20:57           ` Gergely Imre
     [not found] <fa.o8VX4Uax4/>
2007-02-23 14:39 ` Robert Hancock
  -- strict thread matches above, loose matches on Subject: below --
2005-12-15 14:00 Pallipadi, Venkatesh
2005-11-17  8:28 ` JaniD++
2005-12-15  0:48 Pallipadi, Venkatesh
2005-12-15  9:10 ` JaniD++
2005-12-14 21:05 JaniD++
2005-12-14 21:16 ` Arjan van de Ven
2005-12-14 21:31   ` JaniD++

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \ \ \ \ \ \
    --subject='Re: irq balancing question' \

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).