From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750805AbVHXBME (ORCPT ); Tue, 23 Aug 2005 21:12:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750823AbVHXBME (ORCPT ); Tue, 23 Aug 2005 21:12:04 -0400 Received: from omx3-ext.sgi.com ([192.48.171.20]:38367 "EHLO omx3.sgi.com") by vger.kernel.org with ESMTP id S1750805AbVHXBMD (ORCPT ); Tue, 23 Aug 2005 21:12:03 -0400 Date: Wed, 24 Aug 2005 11:03:46 +1000 From: Nathan Scott To: Jens Axboe Cc: Linux Kernel Subject: Re: [PATCH] blk queue io tracing support Message-ID: <20050824010346.GA1021@frodo> References: <20050823123235.GG16461@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20050823123235.GG16461@suse.de> User-Agent: Mutt/1.5.3i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 23, 2005 at 02:32:36PM +0200, Jens Axboe wrote: > Hi, > > This is a little something I have played with. It allows you to see > exactly what is going on in the block layer for a given queue. Currently > it can logs request queueing and building, dispatches, requeues, and > completions. Ah, fabulous. Thanks Jens! > + t.magic = BLK_IO_TRACE_MAGIC | BLK_IO_TRACE_VERSION; > + t.sequence = atomic_add_return(1, &bt->sequence); > + t.time = sched_clock() / 1000; Wouldn't it be better to pass out the highest precision available here & then do the conversion in userspace instead? I guess one might want that little bit more for a RAM disk or something ... actually, talking to one of the SGI people here with alot of experience on IRIX with a similar facility, the msec resolution there is apparently sometimes an issue already with fast storage. cheers. -- Nathan