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Date:      Thu, 10 Jun 1999 09:44:32 -0400
From:      clark@pharlap.com (Clark Jarvis)
To:        freebsd-net@FreeBSD.ORG
Subject:   Re: Poor TCP performance between 2.2.5 and 2.2.8
Message-ID:  <19990610144209302.AAA410@sugar.pharlap.com@clark>
In-Reply-To: <Pine.BSF.3.96.990609164029.13334A-100000@duchess.wagill.com>

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In <Pine.BSF.3.96.990609164029.13334A-100000@duchess.wagill.com>, on
06/09/99 
   at 04:49 PM, Bill <bill@wagill.com> said:

>I continually experience poor TCP performance when sending large files
>from my FreeBSD 2.2.5 box (Linksys ISA NIC) to my Windows 95 box (Linksys
>PCI NIC).  I have an Ethernet hub and I can see the "Collision" light
>illuminate nearly steadily ON when transfering a large file from the
>FreeBSD box to the Windows box (but not the other way around).

>I did post a PR a couple of FreeBSD versions ago, when I first noticed
>the problem, and got one of those blanket "must be your hardware"
>answers.  Since the poor performance is not a big deal in my environment,
>I have not pursued a resolution more insistently.  But, most definitely,
>since about FreeBSD 2.2.3 (give or take a few) I have observed this poor
>TCP performance along with the high volume of network collisions when
>transfering large files out of the FreeBSD box.  This problem was not
>evident in the early 2.x releases.

Check to see if the Linksys W95/PCI driver (DEC chip?  I think) has
settings to adjust the early transmit threshold.  I fixed a similar
problem with Win95 talking to our embedded RTOS by bumping the xmit
threshold up from 512 bytes to 1024 bytes.  Throughput went up by a factor
of 10, almost.  Only found the problem by the constant collision lights on
the hub.  This was over a 100Mb link, but there was a 10Mb setting for
this also.

I realize this may be way off track, but what-the-hey, it was worth a
shot...

-- 
Clark



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