linux-kernel - Re: IRQ balancing on a router

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 3 Oct 2008 16:57:37 +0200
From:	Jan Kasprzak <kas@...muni.cz>
To:	Arjan van de Ven <arjan@...ux.intel.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: IRQ balancing on a router

Arjan van de Ven wrote:
: Jan Kasprzak <kas@...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).

-Yenya

-- 
| Jan "Yenya" Kasprzak  <kas at {fi.muni.cz - work | yenya.net - private}> |
| GPG: ID 1024/D3498839      Fingerprint 0D99A7FB206605D7 8B35FCDE05B18A5E |
| http://www.fi.muni.cz/~kas/    Journal: http://www.fi.muni.cz/~kas/blog/ |
>>  If you find yourself arguing with Alan Cox, you’re _probably_ wrong.  <<
>>     --James Morris in "How and Why You Should Become a Kernel Hacker"  <<
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/