lkml.org 
[lkml]   [2008]   [Oct]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: IRQ balancing on a router
Jan Kasprzak wrote:
> Arjan van de Ven wrote:
> : Jan Kasprzak <kas@fi.muni.cz> wrote:
> : > The result is
> : > that the CPU which receives IRQs for the uplink interface
> : > is 100 % busy (softirq mostly), while the other one is 90% idle.
> :
> : one of the hard cases for irqbalance is that irqbalance doesn't have a
> : way to find out the actual cpu time spend in the handlers. For
> : networking it makes an estimate just based on the number of packets
> : (which is better than nothing)... but that breaks down if you have an
> : non-symmetry in CPU costs per packet like you have.
> :
> : The good news is that irqthreads at least have the potential to solve
> : this "lack of information"; if not, we could consider doing a form of
> : microaccounting for irq handlers....
>
> I am not sure whether this would help. In my case, the most of the
> in-kernel CPU time is not spend in the irq handler per se, but in softirq
> (i.e. checking the packet against iptables rules).

there is some consideration of making softirqs that are raised run as part of the irq thread.
or at least thoughts in that direction.


\
 
 \ /
  Last update: 2008-10-03 17:25    [W:0.067 / U:13.708 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site