Date: Sun, 29 Feb 2004 21:23:47 -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: <6.0.3.0.0.20040229212058.05945af0@209.112.4.2> In-Reply-To: <FE045D4D9F7AED4CBFF1B3B813C85337045D8328@mail.sandvine.com > References: <FE045D4D9F7AED4CBFF1B3B813C85337045D8328@mail.sandvine.com>
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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.
> >
> > Hi,
> > Just curious as to the reasoning behind that ?
>
>@ high packet rates, you don't have enough DMA
>queues available to the em driver, and will drop.
>increasing the number of dma buffers will cause
>problems with cache occupancy. Increasing the HZ
>doesn't have a huge cost.
But why that value ? Did you determine it by trial and error or deduce it
based on some other factors ? Also, is this value optimal for fxp based boxes.
---Mike
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