From: Jiaying Zhang Subject: [RFC PATCH 0/4] ext4: implement DIO read nolocking Date: Tue, 15 Dec 2009 17:36:23 -0800 Message-ID: <5df78e1d0912151736xa1107afrdc5a343ee0f5e0d@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Andrew Morton , Michael Rubin To: ext4 development Return-path: Received: from smtp-out.google.com ([216.239.33.17]:43473 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934381AbZLPBg3 (ORCPT ); Tue, 15 Dec 2009 20:36:29 -0500 Received: from kpbe14.cbf.corp.google.com (kpbe14.cbf.corp.google.com [172.25.105.78]) by smtp-out.google.com with ESMTP id nBG1aP19007531 for ; Wed, 16 Dec 2009 01:36:26 GMT Received: from pwi18 (pwi18.prod.google.com [10.241.219.18]) by kpbe14.cbf.corp.google.com with ESMTP id nBG1a5Ki019119 for ; Tue, 15 Dec 2009 17:36:25 -0800 Received: by pwi18 with SMTP id 18so933007pwi.32 for ; Tue, 15 Dec 2009 17:36:23 -0800 (PST) Sender: linux-ext4-owner@vger.kernel.org List-ID: Hi all, Several weeks ago, we proposed the idea of always allocating uninitialized extent during ext4 DIO write and/or buffer write and convert the extent into initialized after IO complete. This allows us to drop the i_mutex lock during ext4 DIO read, which would help improve ext4 DIO read performance with multiple threads or AIOs running on high-speed SSDs. FYI, here is the email thread referred to: http://marc.info/?l=linux-ext4&m=125513220225086&w=2 Following this email are our RFC patches to implement the proposed idea. We haven't tested these patches much so they are probably very buggy. Any feedback would be greatly appreciated! Regards, Jiaying