Return-path: Received: from ey-out-2122.google.com ([74.125.78.27]:38122 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753154AbYITAB6 (ORCPT ); Fri, 19 Sep 2008 20:01:58 -0400 Received: by ey-out-2122.google.com with SMTP id 6so220250eyi.37 for ; Fri, 19 Sep 2008 17:01:56 -0700 (PDT) Message-ID: (sfid-20080920_020202_716359_D230B170) Date: Fri, 19 Sep 2008 17:01:56 -0700 From: "Steven Noonan" To: "Luis R. Rodriguez" Subject: Re: [ath9k-devel] ath9k: massive unexplained latency in 2.6.27 (rc5, rc6, probably others) Cc: "Luis Rodriguez" , "Senthilkumar Balasubramanian" , "Ingo Molnar" , "ath9k-devel@lists.ath9k.org" , linux-wireless , LKML In-Reply-To: <20080919235305.GD11665@tesla> MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 References: <20080919030125.GG7408@tesla> <20080919142801.GA5816@senthil-lnx.users.atheros.com> <20080919175824.GA5626@senthil-lnx.users.atheros.com> <20080919182322.GB7027@tesla> <20080919235305.GD11665@tesla> Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, Sep 19, 2008 at 4:53 PM, Luis R. Rodriguez wrote: > On Fri, Sep 19, 2008 at 04:31:20PM -0700, Steven Noonan wrote: >> >> I'm seeing the same latency issue I reported originally with the latest >> -tip kernel and WITHOUT irqpoll. > > Damn it. > >> Apparently there's something else to this... > > Steven, > > Can you reproduce this? If so can you tell us how? If you can reproduce > can you try to test this with wireless-testing as well? That is still > based on 2.6.26-rc6 but its just has all the new wireless development > stuff queued up for 2.6.28 so far. Everything else is the same. It's a weird problem, because I'm able to reproduce it by running a kernel with ath9k loaded for a few hours. In this particular case, I only ran this kernel for about 3.5 hours , but the delay when VT switching was getting noticeable. Unload/reload of ath9k and the latency disappeared again. It's definitely ath9k's doing, but I don't know how. I'm finding the delay is most noticeable after 7 hours uptime with ath9k loaded. I'll pull wireless-testing and run that kernel for another 8 hours. What's the URL for the repo? Surely you don't mean the wireless-testing on git.kernel.org that hasn't been touched for almost a week? I kind of wish there was a better debugging facility in ath9k. With ATH_DBG_INTERRUPTS, I see several hundred messages per second, which fills log files up like crazy (I switched to ftrace_printk as Ingo suggested, which has alleviated this somewhat). Is there a way to make it less verbose (perhaps so that it prints data at a rate of no more than 2 or 3 messages per second)? Or maybe the rate at which it prints this stuff is indicative something's wrong? - Steven