linux-kernel - Re: [E1000-devel] e1000 1sec latency problem

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Message-ID: <47AB49F3.301@intel.com>
Date:	Thu, 07 Feb 2008 10:12:03 -0800
From:	"Kok, Auke" <auke-jan.h.kok@...el.com>
To:	Max Krasnyansky <maxk@...lcomm.com>
CC:	Pavel Machek <pavel@....cz>, e1000-devel@...ts.sourceforge.net,
	jesse.brandeburg@...el.com,
	kernel list <linux-kernel@...r.kernel.org>,
	john.ronciak@...el.com, jeffrey.t.kirsher@...el.com
Subject: Re: [E1000-devel] e1000 1sec latency problem

Max Krasnyansky wrote:
> Kok, Auke wrote:
>> Max Krasnyansky wrote:
>>> So you don't think it's related to the interrupt coalescing by any chance ?
>>> I'd suggest to try and disable the coalescing and see if it makes any difference.
>>> We've had lots of issues with coalescing misbehavior. Not this bad (ie 1 second) though.
>>>
>>> Add this to modprobe.conf and reload e1000 module
>>>
>>> options e1000 RxIntDelay=0,0 RxAbsIntDelay=0,0 InterruptThrottleRate=0,0 TxIntDelay=0,0 TxAbsIntDelay=0,0
>> that can't be the problem. irq moderation would only account for 2-3ms variance
>> maximum.
> Oh, I've definitely seen worse than that. Not as bad as a 1second though. Plus you're talking
> about the case when coalescing logic is working as designed ;-). What if there is some kind of 
> bug where timer did not expire or something.

we don't use a software timer in e1000 irq coalescing/moderation, it's all in
hardware, so we don't have that problem at all. And I certainly have never seen
anything you are referring to with e1000 hardware, and I do not know of any bug
related to this.

are you maybe confused with other hardware?

feel free to demonstrate an example...

Cheers,

Auke
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