From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dean Hildebrand Subject: Re: [NFS] read-ahead in NFS server Date: Sun, 30 Dec 2007 20:33:45 -0800 Message-ID: <47787129.7060809@gmail.com> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: nfs@lists.sourceforge.net To: saeed bishara Return-path: Received: from neil.brown.name ([220.233.11.133]:36447 "EHLO neil.brown.name" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752415AbXLaEd4 (ORCPT ); Sun, 30 Dec 2007 23:33:56 -0500 Received: from brown by neil.brown.name with local (Exim 4.63) (envelope-from ) id 1J9CLa-0002Lq-0Y for linux-nfs@vger.kernel.org; Mon, 31 Dec 2007 15:33:54 +1100 In-Reply-To: Sender: linux-nfs-owner@vger.kernel.org List-ID: My understanding is that readahead is a client concept, in the sense that the nfs client and ext3 are both clients. The NFS client performs readahead, which is carried out as a series of 32 KB requests. The exported file system client, ext3 in your case, will decide how best to react to these requests and perform readahead, etc as necessary. The NFS server only relays the I/O requests to the underlying file system, although it might delay (on linux) or gather the requests for maximum performance. I believe ext3 uses the standard linux readahead mechanism, so readahead should be occurring. How are you determining on the server that ext3 is only issuing 32KB requests to the disks? I bet that the nfs server is passing 32 KB requests to ext3, which in turn is issuing larger requests to the disks. Another thing to do is on linux you can increase the rsize to 1 MB to get larger chunks out of the disks. Dean saeed bishara wrote: > Hi, > my NFS server seems not to utilize the read-ahead feature, my exported > dir is located on ext3 fs over sata disk. the sata controller can > issue commands up to 1MB, also I modified the read ahead under the sys > to 1MB. but when the client do reads in 32KB chunks (rsize), I can see > in the server side that all IOs are ~32KB. my kernel version is > 2.6.22.7. > does the NFS server utilizes the read-ahead feature? what should I do > to enable it? > > please CC me as I'm not subscribed to this list. > saeed > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2005. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > NFS maillist - NFS@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/nfs > _______________________________________________ > Please note that nfs@lists.sourceforge.net is being discontinued. > Please subscribe to linux-nfs@vger.kernel.org instead. > http://vger.kernel.org/vger-lists.html#linux-nfs > > - > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2005. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ NFS maillist - NFS@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/nfs _______________________________________________ Please note that nfs@lists.sourceforge.net is being discontinued. Please subscribe to linux-nfs@vger.kernel.org instead. http://vger.kernel.org/vger-lists.html#linux-nfs