From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from gate.crashing.org (gate.crashing.org [63.228.1.57]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id 32BEAB7E4A for ; Fri, 14 May 2010 07:28:49 +1000 (EST) Subject: Re: "event-scan failed" logflood From: Benjamin Herrenschmidt To: pacman@kosh.dhis.org In-Reply-To: <20100513111603.3352.qmail@kosh.dhis.org> References: <20100513111603.3352.qmail@kosh.dhis.org> Content-Type: text/plain; charset="UTF-8" Date: Fri, 14 May 2010 07:28:24 +1000 Message-ID: <1273786104.21352.190.camel@pasglop> Mime-Version: 1.0 Cc: linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, 2010-05-13 at 06:16 -0500, pacman@kosh.dhis.org wrote: > Benjamin Herrenschmidt writes: > > > > Well, first it should be called once per second, not 60 times per > > second, so something is wrong there... > > Actually I think it was happening a lot more than 60 times per second, and > klogd was losing most of the messages because they came too fast. When > running the new kernel, vmstat shows 170000 context switches per second (and > CPU usage never going below 5%) even when everything should be idle. > > My next experiment was to hack rtas_init to return 0 unconditionally. Now > everything still runs fine, and the context switches per second are back down > in the 2-digit range. > > > > > Then, it wouldn't surprise me if the Pegasos RTAS didn't implement > > the event scan properly. Maybe we failed silently before that ? I > > doubt it's necessary there anyways. > > If I'm reading things correctly, rtas-event-scan-rate is the key to the > frequency of attempts. And rtasd.c didn't expect this: > > $ od -t x1 /proc/device-tree/rtas/rtas-event-scan-rate > 0000000 00 00 00 00 > 0000004 Ok, that gives us a good thing to use to not do the scanning then. If that's 0 then we assume it's a bogus OF and we disable the scan completely. I'll do a patch later today, though feel free to beat me to it. Cheers, Ben.