From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Christie Subject: Re: [Patch] SCSI I/O statistics Date: Tue, 26 Sep 2006 16:45:54 -0500 Message-ID: <45199F92.106@cs.wisc.edu> References: <1159286194.2925.5.camel@dyn-9-152-230-71.boeblingen.de.ibm.com> <20060926103930.471b75a5.akpm@osdl.org> <20060926182347.GH5017@parisc-linux.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from sabe.cs.wisc.edu ([128.105.6.20]:57265 "EHLO sabe.cs.wisc.edu") by vger.kernel.org with ESMTP id S964845AbWIZVqJ (ORCPT ); Tue, 26 Sep 2006 17:46:09 -0400 In-Reply-To: <20060926182347.GH5017@parisc-linux.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Matthew Wilcox Cc: Andrew Morton , Martin Peschke , linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org Matthew Wilcox wrote: > On Tue, Sep 26, 2006 at 10:39:30AM -0700, Andrew Morton wrote: >> - Should it have been done at the block layer rather than at the scsi layer? > > This was already mentioned when he sent it to linux-scsi a few days ago. > There are scsi commands which bypass the block layer, such as SG_IO, and I do not think any command completely bypasses the block layer now. SG_IO, tape, sd and scanning insertion go through blk_execute_rq_nowait for insertion. For completion they go through blk_complete_request + end_that_request_first/last in the normal path and blk_complete_request + blk_requeue_request in the retry path. > block layer stats can make an extremely busy disc look not busy. > - > To unsubscribe from this list: send the line "unsubscribe linux-scsi" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html