Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932101AbVJGIN3 (ORCPT ); Fri, 7 Oct 2005 04:13:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932104AbVJGIN3 (ORCPT ); Fri, 7 Oct 2005 04:13:29 -0400 Received: from fmr16.intel.com ([192.55.52.70]:51139 "EHLO fmsfmr006.fm.intel.com") by vger.kernel.org with ESMTP id S932101AbVJGIN1 convert rfc822-to-8bit (ORCPT ); Fri, 7 Oct 2005 04:13:27 -0400 X-MimeOLE: Produced By Microsoft Exchange V6.5.7226.0 Content-class: urn:content-classes:message MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 8BIT Subject: RE: [RFC] add sysfs to dynamically control blk request tag maintenance Date: Fri, 7 Oct 2005 01:13:21 -0700 Message-ID: X-MS-Has-Attach: X-MS-TNEF-Correlator: Thread-Topic: [RFC] add sysfs to dynamically control blk request tag maintenance Thread-Index: AcXLFhYoKxsCkWQuQ9CUfyrHTCj8PgAADN5w From: "Chen, Kenneth W" To: "Jens Axboe" Cc: X-OriginalArrivalTime: 07 Oct 2005 08:13:22.0446 (UTC) FILETIME=[FBD18AE0:01C5CB16] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1842 Lines: 46 Jens Axboe wrote on Friday, October 07, 2005 1:08 AM > > It's probably a very small number that I'm chasing with avoiding blk > > layer tagging. Nevertheless, any number no matter how small, is a gold > > mine to me :-) > > > > Latest execution profile taken with 2.6.14-rc2 kernel with "industry > > standard transaction processing database workload". First column is > > clock ticks (a direct measure of time), 2nd column is instruction > > retired, > > and 3rd column is number of L3 misses occurred inside the function. > > > > Symbol Clockticks Inst. Retired L3 Misses > > scsi_request_fn 8.12% 9.27% 11.18% > > Schedule 6.52% 4.93% 7.26% > > scsi_end_request 4.44% 3.59% 6.76% > > __blockdev_direct_IO 4.28% 4.38% 3.98% > > __make_request 3.59% 4.16% 3.47% > > __wake_up 2.46% 1.56% 3.33% > > dio_bio_end_io 2.14% 1.67% 3.18% > > aio_complete 2.05% 1.27% 3.56% > > kmem_cache_free 1.95% 1.70% 0.71% > > kmem_cache_alloc 1.45% 1.84% 0.45% > > put_page 1.42% 0.60% 1.27% > > follow_hugetlb_page 1.41% 0.75% 1.27% > > __generic_file_aio_read 1.37% 0.36% 1.68% > > The above looks pretty much as expected. What change in profile did you > see when eliminating the blk_queue_end_tag() call? I haven't make any measurement yet. The original patch was an RFC, and I want to hear opinions from the experts first. I will do a measurement with the change in qla2x00 driver and I will let you know how much difference does it make. Most likely, clock ticks in scsi_request_fn and scsi_end_request should be reduced. It will be interesting to see L3 misses stats as well. - Ken - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/