Date: Mon, 01 Mar 2004 11:12:07 -0500 From: Mike Tancsa <mike@sentex.net> To: Don Bowman <don@sandvine.com> Cc: freebsd-hackers@freebsd.org Subject: RE: em0, polling performance, P4 2.8ghz FSB 800mhz Message-ID: <6.0.3.0.0.20040301105700.072c4f00@209.112.4.2> In-Reply-To: <FE045D4D9F7AED4CBFF1B3B813C85337045D832C@mail.sandvine.com > References: <FE045D4D9F7AED4CBFF1B3B813C85337045D832C@mail.sandvine.com>
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At 09:38 PM 29/02/2004, Don Bowman wrote:
>From: Mike Tancsa [mailto:mike@sentex.net]
> > At 08:44 PM 29/02/2004, Don Bowman wrote:
> > >From: Mike Tancsa [mailto:mike@sentex.net]
> > > >
> > > > On Sat, 28 Feb 2004 23:17:44 -0500, in
> > sentex.lists.freebsd.hackers >
> > > > >If you want to spend more time in kernel, perhaps change
> > > > >
> > > > >I might have HZ @ 2500 as well.
>I picked 2500 as the best for my system. Its higher than
>allowed by rfc1323 and PAWS [kern/61404], but not by so much
>that i anticipate a problem.
Do you run the box with the supplied patch ? On the firewall device I was
thinking of experimenting with, I do have long TCP sessions that it sounds
like HZ=2500 would break.
>For my target packets per second
>rate, it means that i can use a reasonable number of dma
>descriptors. I found that bridging performance in particular
>needs the higher hz to avoid dropping packets, to improve
>its performance.
In terms of fiddling with the em tunables, what are the drawbacks of moving
from 256 to 512 on
EM_MAX_TXD
EM_MAX_RXD
>more buffers == better ability to handle latency
>bursts, but worse for cache occupancy.
Buffers as is net.inet.ip.intr_queue_maxlen ?
Thanks,
---Mike
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