From: Stephen Hemminger <shemminger@vyatta.com>
To: Marek Kierdelewicz <marek@piasta.pl>
Cc: Rick Jones <rick.jones2@hp.com>, netfilter@vger.kernel.org
Subject: Re: netfilter performance dependent on arch
Date: Tue, 7 Feb 2012 11:11:20 -0800 [thread overview]
Message-ID: <20120207111120.1d9ab37a@nehalam.linuxnetplumber.net> (raw)
In-Reply-To: <20120207195411.05a70f67@catus>
On Tue, 7 Feb 2012 19:54:11 +0100
Marek Kierdelewicz <marek@piasta.pl> wrote:
> >> Can anyone point me to some performance comparison of netfilter on
> >> i686 and x86_64? I have a few linux routers doing a lot of
> >> firewalling and QoS. Currently those routers use i686 arch on 64-bit
> >> hardware. Would I notice any performance gain after moving to 64-bit
> >> kernel?
>
> >Apart from the obvious "Try it on your workload and see." suggestion,
> >you could I suppose make the assumption that a netfilter workload
> >looks similar to one or more components of something like
>
> Thanks for the response. Anyway moments ago I found answer to the first
> question on vyatta forum here:
> http://www.vyatta.org/forum/viewtopic.php?t=823&sid=3cec85f2cf7866ca26040ec491415ee1
That information is out of date.
The bulk of the slow down in 64 bit was due to the fact that IOMMU
(CONFIG_DMAR) was enabled. The IOMMU requires programming DMA registers
on each packet which explains the extra overhead. After disabling
DMA remapping, the 64 bit kernel is faster because the compiler has
more registers and can generate better code.
next prev parent reply other threads:[~2012-02-07 19:11 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-07 17:34 netfilter performance dependent on arch Marek Kierdelewicz
2012-02-07 18:23 ` Rick Jones
2012-02-07 18:54 ` Marek Kierdelewicz
2012-02-07 19:11 ` Stephen Hemminger [this message]
2012-02-07 19:48 ` Marek Kierdelewicz
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:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20120207111120.1d9ab37a@nehalam.linuxnetplumber.net \
--to=shemminger@vyatta.com \
--cc=marek@piasta.pl \
--cc=netfilter@vger.kernel.org \
--cc=rick.jones2@hp.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox