From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754470AbaIKNgj (ORCPT ); Thu, 11 Sep 2014 09:36:39 -0400 Received: from mailout1.samsung.com ([203.254.224.24]:16233 "EHLO mailout1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753400AbaIKNgh (ORCPT ); Thu, 11 Sep 2014 09:36:37 -0400 X-AuditID: cbfee61a-f79e46d00000134f-71-5411a563312a From: Bartlomiej Zolnierkiewicz To: Alexander Gordeev Cc: Tejun Heo , linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org Subject: Re: [PATCH RESEND 0/1] AHCI: Optimize interrupt processing Date: Thu, 11 Sep 2014 15:36:31 +0200 Message-id: <4127129.ClfhyhZXo5@amdc1032> User-Agent: KMail/4.8.4 (Linux/3.2.0-54-generic-pae; KDE/4.8.5; i686; ; ) In-reply-to: <20140911124248.GA18490@dhcp-27-160.brq.redhat.com> References: <20130521235003.GE6985@mtj.dyndns.org> <20140911124248.GA18490@dhcp-27-160.brq.redhat.com> MIME-version: 1.0 Content-transfer-encoding: 7Bit Content-type: text/plain; charset=us-ascii X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFjrCLMWRmVeSWpSXmKPExsVy+t9jAd3kpYIhBqvuGlu8fH6azeLYjkdM Fpd3zWGz+LX8KKMDi8emVZ1sHu/3XWXz+LxJLoA5issmJTUnsyy1SN8ugSvj5+1W1oKvHBUv j5xnamCcwN7FyMkhIWAi8ezSayhbTOLCvfVsXYxcHEICixglrnRMZ4FwWpgk1rTvYgWpYhOw kpjYvooRxBYR0JZo2/wNrJtZIEJi97HJYDXCAs4S8//vZwKxWQRUJa7sPMEMYvMKaEq8+zYR rFdUwFNix/aVbCA2p4CDxP7e/awQy6YySryd0cQG0SAo8WPyPRaIBfIS+/ZPZYWwtSTW7zzO NIFRYBaSsllIymYhKVvAyLyKUTS1ILmgOCk911CvODG3uDQvXS85P3cTIzhsn0ntYFzZYHGI UYCDUYmHt4JFMESINbGsuDL3EKMEB7OSCK/zQqAQb0piZVVqUX58UWlOavEhRmkOFiVx3gOt 1oFCAumJJanZqakFqUUwWSYOTqkGRs9e82V+lUphlZ7/2i5onK6eqqTfsbCatf1T3Jz7/CxT 6kWV5zM1rWY4yKG2qt3d+BOr1bbzDgoPtp3Oc+0P3XXZ9IHc/a3Fn5Pul/U9YDyydlpds1vB i91ZvLzh4fNuOXtLuy9et4+9l7sshX2apt/i85fYYmZv/mpUv6ukR+L6z5QA+fW3lFiKMxIN tZiLihMBSLo7KlcCAAA= Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Thursday, September 11, 2014 02:42:49 PM Alexander Gordeev wrote: > The numbers are taken by running 'dd if=/dev/sd{a,b} of=/dev/null' > in parallel. All time values are in us. > > Before this update host lock average holdtime was 2.45 and > average waittime was 1.24. After the update average holdtime > dropped to 0.29 (about eight times) while average waittime > decreased to 0.58 (about two times). > > Also, port events are handled with local interrupts enabled > and compete on individual per-port locks with average holdtime > 1.25 and average waittime 1.48. So combined average holdtime > spent while holding host and port locks decreased from 2.45 to > 0.29 + 1.25 = 1.54 (about 1.6 times). > > The downside of this change is introduction of a kernel thread. > > The upside is shorter access time to port locks and moving port > interrupts handling out of the hardware interrupt context. IMHO it would be great to put the above results into the patch description (it now looks a bit skimpy). Best regards, -- Bartlomiej Zolnierkiewicz Samsung R&D Institute Poland Samsung Electronics