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Message-ID: <2007014.RQqn1EBPtM@h2o.as.studentenwerk.mhn.de>
Date: Wed, 23 Oct 2013 18:05:22 +0200
From: Wolfgang Walter <linux@...m.de>
To: Steffen Klassert <steffen.klassert@...unet.com>
Cc: David Miller <davem@...emloft.net>, hannes@...essinduktion.org,
netdev@...r.kernel.org, klassert@...hematik.tu-chemnitz.de
Subject: Re: Big performance loss from 3.4.63 to 3.10.13 when routing ipv4
Am Mittwoch, 23. Oktober 2013, 14:04:34 schrieb Steffen Klassert:
> On Wed, Oct 23, 2013 at 01:33:14PM +0200, Wolfgang Walter wrote:
> > Am Mittwoch, 23. Oktober 2013, 10:12:55 schrieb Steffen Klassert:
> > > On Tue, Oct 22, 2013 at 03:46:38PM -0400, David Miller wrote:
> > > > I think we should resolve this soon, even bumping it to 2048 or 4096
> > > > and leaving it at that would be I think acceptable.
> > >
> > > Yes, of course. Let's use 4096 as the default for ipv4 and ipv6.
> > > I'll take care of it next week.
> >
> > I don't know what this value actually means. But on 3.4.x it is much
> > higher. On a machine with 512MB ram it is 32768, on a machine with 1GB
> > ram it is 262144 and with 16GB ram it is 4194304.
>
> Before we removed the routing cache, the gc threshold was scaled along
> with the maximum routing cache size (ip_rt_max_size). With the routing
> cache removal, we lost the possibility to scale with ip_rt_max_size
> and we had to choose a static default. Maybe we can try to tweak the
> gc threshold again with the available memory somehow later. But to fix
> it now, we need to find a reasonable default value. Would a default of
> 4096 meet your requirements?
Can't say that at the moment. I can test it tonight. I assume that I don't
need more than 262144 even on the large router as it worked on older hardware
with less memory (with 3.4.x kernels). No router of us had a value less then
32768 with 3.4.x.
Regards,
--
Wolfgang Walter
Studentenwerk München
Anstalt des öffentlichen Rechts
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