From mboxrd@z Thu Jan 1 00:00:00 1970 From: Fengguang Wu Subject: Re: [PATCH] mm: readahead: remove redundant ra_pages in file_ra_state Date: Thu, 25 Oct 2012 10:38:08 +0800 Message-ID: <20121025023808.GA23462@localhost> References: <1350996411-5425-1-git-send-email-casualfisher@gmail.com> <20121023224706.GR4291@dastard> <20121024201921.GX4291@dastard> <20121025015014.GC29378@dastard> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Dave Chinner , akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org To: YingHang Zhu Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-Id: linux-fsdevel.vger.kernel.org Hi YingHang, > Actually I've talked about it with Fengguang, he advised we should unify the > ra_pages in struct bdi and file_ra_state and leave the issue that > spreading data > across disks as it is. > Fengguang, what's you opinion about this? Yeah the two ra_pages may run out of sync for already opened files, which could be a problem for long opened files. However as Dave put it, a device's max readahead size is typically a static value that can be set at mount time. So, the question is: do you really hurt from the old behavior that deserves this code change? I agree with Dave that the multi-disk case is not a valid concern. In fact, how can the patch help that case? I mean, if it's two fuse files lying in two disks, it *was* not a problem at all. If it's one big file spreading to two disks, it's a too complex scheme to be practically manageable which I doubt if you have such a setup. Thanks, Fengguang -- 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