From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f53.google.com (mail-pa0-f53.google.com [209.85.220.53]) by kanga.kvack.org (Postfix) with ESMTP id CD6F96B0037 for ; Tue, 17 Dec 2013 04:32:06 -0500 (EST) Received: by mail-pa0-f53.google.com with SMTP id hz1so4210040pad.12 for ; Tue, 17 Dec 2013 01:32:06 -0800 (PST) Received: from m59-178.qiye.163.com (m59-178.qiye.163.com. [123.58.178.59]) by mx.google.com with ESMTP id eq2si11215260pbb.82.2013.12.17.01.32.02 for ; Tue, 17 Dec 2013 01:32:03 -0800 (PST) Message-ID: <52B019F5.7020505@ubuntukylin.com> Date: Tue, 17 Dec 2013 17:31:33 +0800 From: Li Wang MIME-Version: 1.0 Subject: Re: [PATCH 0/5] VFS: Directory level cache cleaning References: <52AFC020.10403@ubuntukylin.com> <20131217035847.GA10392@parisc-linux.org> <52AFFBE3.8020507@ubuntukylin.com> <52B01594.80001@huawei.com> In-Reply-To: <52B01594.80001@huawei.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Li Zefan Cc: Matthew Wilcox , Cong Wang , Alexander Viro , Sage Weil , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, LKML , Yunchuan Wen This extension is just add-on extension. The original debugging capability is still there, and more flexible debugging is now allowed. On 2013/12/17 17:12, Li Zefan wrote: > On 2013/12/17 15:23, Li Wang wrote: >> If we do wanna equip fadvise() with directory level page cache cleaning, >> this could be solved by invoking (inode_permission() || capable(CAP_SYS_ADMIN)) before manipulating the page cache of that inode. >> We think the current extension to 'drop_caches' has a complete back >> compatibility, the old semantics keep unchanged, and with add-on >> features to do finer granularity cache cleaning should be also >> desirable. >> > > I don't think you can extend the drop_caches interface this way. It should > be used for debuging only. > > commit 9d0243bca345d5ce25d3f4b74b7facb3a6df1232 > Author: Andrew Morton > Date: Sun Jan 8 01:00:39 2006 -0800 > > [PATCH] drop-pagecache > > Add /proc/sys/vm/drop_caches. When written to, this will cause the kernel to > discard as much pagecache and/or reclaimable slab objects as it can. THis > operation requires root permissions. > > ... > > This is a debugging feature: useful for getting consistent results between > filesystem benchmarks. We could possibly put it under a config option, but > it's less than 300 bytes. > > Also see http://lkml.org/lkml/2013/7/26/230 > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org