From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422777AbXDXRYw (ORCPT ); Tue, 24 Apr 2007 13:24:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422780AbXDXRYw (ORCPT ); Tue, 24 Apr 2007 13:24:52 -0400 Received: from e33.co.us.ibm.com ([32.97.110.151]:38182 "EHLO e33.co.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422777AbXDXRYu (ORCPT ); Tue, 24 Apr 2007 13:24:50 -0400 Date: Tue, 24 Apr 2007 12:24:48 -0500 To: Benjamin Herrenschmidt Cc: Christoph Hellwig , "Eric W. Biederman" , ", containers@lists.osdl.org, Oleg Nesterov , linux-kernel@vger.kernel.org, Paul Mackerras , linux-s390@vger.kernel.org, linuxppc-dev@ozlabs.org Subject: Re: [PATCH] powerpc pseries eeh: Convert to kthread API Message-ID: <20070424172448.GX31947@austin.ibm.com> References: <11769695763104-git-send-email-ebiederm@xmission.com> <20070422123155.GF20763@infradead.org> <20070423205020.GR31947@austin.ibm.com> <1177378733.14873.52.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1177378733.14873.52.camel@localhost.localdomain> User-Agent: Mutt/1.5.11 From: linas@austin.ibm.com (Linas Vepstas) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 24, 2007 at 11:38:53AM +1000, Benjamin Herrenschmidt wrote: > > The only reason for using threads here is to get the error recovery > > out of an interrupt context (where errors may be detected), and then, > > an hour later, decrement a counter (which is how we limit these to > > 6 per hour). Thread reaping is "trivial", the thread just exits > > after an hour. > > In addition, it should be a thread and not done from within keventd > because : > > - It can take a long time (well, relatively but still too long for a > work queue) Uhh, 15 or 20 seconds even. That's a long time by any kernel standard. > - The driver callbacks might need to use keventd or do flush_workqueue > to synchronize with their own workqueues when doing an internal > recovery. > > > Since these are events rare, I've no particular concern about > > performance or resource consumption. The current code seems > > to work just fine. :-) > > I think moving to kthread's is cleaner (just a wrapper around kernel > threads that simplify dealing with reaping them out mostly) and I agree > with Christoph that it would be nice to be able to "fire off" kthreads > from interrupt context.. in many cases, we abuse work queues for things > that should really done from kthreads instead (basically anything that > takes more than a couple hundred microsecs or so). It would be nice to have threads that can be "fired off" from an interrupt context. That would simplify the EEH code slightly (removing a few dozen lines of code that do this bounce). I presume that various device drivers might find this useful as well. --linas