From: Sunil Mushran Subject: Re: [RFC] fadvise: add more flags to provide a hint for block allocation Date: Mon, 05 Mar 2012 20:26:03 -0800 Message-ID: <4F5591DB.4060807@oracle.com> References: <20120305125029.GA5121@gmail.com> <4F55189B.4080507@oracle.com> <20120306023505.GA7728@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org Return-path: Received: from acsinet15.oracle.com ([141.146.126.227]:36008 "EHLO acsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965027Ab2CFE0K (ORCPT ); Mon, 5 Mar 2012 23:26:10 -0500 In-Reply-To: <20120306023505.GA7728@gmail.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: On 3/5/2012 6:35 PM, Zheng Liu wrote: > No, _RANDOM means that file system doesn't need to try its best to find > a proper position to allocate some blocks for this file. Furthermore, > currently random IOs seem that they are not obviously slower than > sequential IOs in Flash/SSD device. For example, when users know a file > that is accessed infrequently, they can put this file in a corner, such > as in some discontinuously blocks. Then sequential blocks are reserved > for the file that needs to be accessed frequently and users can obtain > the better performance. Then FADV_ALLOC_HOT_REGION and FADV_ALLOC_COLD_REGION are probably better terms.