linux-kernel - Re: [ath9k-devel] ath9k: massive unexplained latency in 2.6.27 (rc5, rc6, probably others)

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Message-ID: <20080919030125.GG7408@tesla>
Date:	Thu, 18 Sep 2008 20:01:25 -0700
From:	"Luis R. Rodriguez" <lrodriguez@...eros.com>
To:	Steven Noonan <steven@...inklabs.net>
CC:	Luis Rodriguez <Luis.Rodriguez@...eros.com>,
	Ingo Molnar <mingo@...e.hu>,
	"ath9k-devel@...ts.ath9k.org" <ath9k-devel@...ts.ath9k.org>,
	linux-wireless <linux-wireless@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [ath9k-devel] ath9k: massive unexplained latency in 2.6.27
	(rc5, rc6, probably others)

On Thu, Sep 18, 2008 at 07:52:16PM -0700, Steven Noonan wrote:
> This IRQ debugging is lots of fun. My /var/log/messages jumped in size
> to 241MB. :)
> 
> My test case was a file transfer that basically copies 50MB from a
> remote machine's /dev/urandom and writes it to /dev/null locally. That
> should be a pretty nice large RX. And jeez, I'm seeing tremendous
> download speeds now and I have no idea what is different about my
> configuration. I'm getting up to 24 megabit per second transfer rates
> (actual), which is incredibly unusual for ath9k.
> 
> I wasn't able to reproduce the IRQ problems on -tip or Linus' current
> tree (both with the group rekeying fix applied, which may or may not
> be a good idea for reproducing the issue). Even tried doing
> rmmod/modprobe in fast succession multiple times. Couldn't get it to
> throw up.
> 
> I wonder... My rmmod/modprobe originally was used after the improper
> group rekeying before in order to get it back to normal. Perhaps the
> encryption has to go wonky before this IRQ issue surfaces? Another
> possibility is the earlier mentioned "ACPI: EC: GPE storm detected,
> disabling EC GPE". I don't know if it's related or not, but I haven't
> waited for it to show up before testing.
> 
> Oh well, if the IRQ problem resurfaces (or if I get a ridiculous
> latency tomorrow morning with irqpoll off), I'll try to get some
> useful data to help debug it.

Thanks for testing, and glad to see this is resolved.

  Luis
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