From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ebiederm.dsl.xmission.com (ebiederm.dsl.xmission.com [166.70.28.69]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTP id CAFDCDDEE4 for ; Tue, 24 Apr 2007 12:24:42 +1000 (EST) From: ebiederm@xmission.com (Eric W. Biederman) To: Benjamin Herrenschmidt Subject: Re: [PATCH] powerpc pseries eeh: Convert to kthread API References: <11769695763104-git-send-email-ebiederm@xmission.com> <20070422123155.GF20763@infradead.org> <20070423205020.GR31947@austin.ibm.com> <1177378733.14873.52.camel@localhost.localdomain> Date: Mon, 23 Apr 2007 20:08:42 -0600 In-Reply-To: <1177378733.14873.52.camel@localhost.localdomain> (Benjamin Herrenschmidt's message of "Tue, 24 Apr 2007 11:38:53 +1000") Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: ", linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, Christoph Hellwig , linuxppc-dev@ozlabs.org, Paul Mackerras , containers@lists.osdl.org, Oleg Nesterov List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Benjamin Herrenschmidt writes: >> 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) > > - 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). On that note does anyone have a problem is we manage the irq spawning safe kthreads the same way that we manage the work queue entries. i.e. by a structure allocated by the caller? Eric