Subject: Re: Should Alpha PCI code manage latency timers?
To: None <port-alpha@NetBSD.ORG, tech-kern@NetBSD.ORG>
From: List Mail User <>
List: tech-kern
Date: 01/26/2005 00:38:12
>From Wed Jan 26 00:17:07 2005
>Date: Wed, 26 Jan 2005 03:16:13 -0500 (EST)
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>[lots clipped]
>[ On Tuesday, January 25, 2005 at 21:26:52 (-0800), List Mail User wrote: ]
>> Subject: Re: Should Alpha PCI code manage latency timers?
>> 	Here, unlike the Sun Ultra 10 reported before, both of the values for
>> your "Q Logic" cards look incorrect.
>Hmmm.... they're the few things on this machine that actually seem to
>work exactly as expected.  (unlike any GigE card I've tried!)
>Though I haven't yet tried to pull data off the FC arrays while pushing
>it out the network at the same time.....
>[rest clipped]
>						Greg A. Woods
>H:+1 416 218-0098  W:+1 416 489-5852 x122  VE3TCP  RoboHack <>
>Planix, Inc. <>          Secrets of the Weird <>
	I would expect the Q logic controllers to work since everybody else
gives them "enough" time.  I'd simply expect them to interfere with other
devices.  Unfortunately most common the expected failure mode for a bad
latency setting is that the "bad" device works, just others may not.

	The test would be to see if you can generate a high and continuous load
using the Q Logic FC cards, and see problems with other devices.  Likely the GigE
cards would show problems if they were also running full out - even though their
setting look correct, they would miscalculate the required buffer size, and you
would expect underruns to occur - does this explanation match the problems which
you have seen?  Your comment about all GigE cards misbehaving would seem to back
this up - Do you know what kind of errors you get on the network cards?  I'd bet
on short packets and/or underruns (i.e. the grant is removed before they "expect"
to be complete with the transaction).

	Paul Shupak