From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f42.google.com (mail-wg0-f42.google.com [74.125.82.42]) by kanga.kvack.org (Postfix) with ESMTP id E9A226B0036 for ; Thu, 21 Nov 2013 17:39:09 -0500 (EST) Received: by mail-wg0-f42.google.com with SMTP id k14so670813wgh.3 for ; Thu, 21 Nov 2013 14:39:09 -0800 (PST) Received: from mail-wi0-x236.google.com (mail-wi0-x236.google.com [2a00:1450:400c:c05::236]) by mx.google.com with ESMTPS id hi12si1601703wib.1.2013.11.21.14.39.09 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Thu, 21 Nov 2013 14:39:09 -0800 (PST) Received: by mail-wi0-f182.google.com with SMTP id en1so1809046wid.3 for ; Thu, 21 Nov 2013 14:39:09 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <528D570D.3020006@oracle.com> References: <1384976973-32722-1-git-send-email-ddstreet@ieee.org> <528D570D.3020006@oracle.com> From: Dan Streetman Date: Thu, 21 Nov 2013 17:38:49 -0500 Message-ID: Subject: Re: [PATCH v2] mm/zswap: change zswap to writethrough cache Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Bob Liu Cc: Seth Jennings , linux-mm@kvack.org, linux-kernel , Minchan Kim , Weijie Yang On Wed, Nov 20, 2013 at 7:42 PM, Bob Liu wrote: > Hi Dan, > > On 11/21/2013 03:49 AM, Dan Streetman wrote: >> Currently, zswap is writeback cache; stored pages are not sent >> to swap disk, and when zswap wants to evict old pages it must >> first write them back to swap cache/disk manually. This avoids >> swap out disk I/O up front, but only moves that disk I/O to >> the writeback case (for pages that are evicted), and adds the >> overhead of having to uncompress the evicted pages, and adds the >> need for an additional free page (to store the uncompressed page) >> at a time of likely high memory pressure. Additionally, being >> writeback adds complexity to zswap by having to perform the >> writeback on page eviction. >> > > Good work! > >> This changes zswap to writethrough cache by enabling >> frontswap_writethrough() before registering, so that any >> successful page store will also be written to swap disk. All the >> writeback code is removed since it is no longer needed, and the >> only operation during a page eviction is now to remove the entry >> from the tree and free it. >> > > Could you do some testing using eg. SPECjbb? And compare the result with > original zswap. Sure, I have a small test program that I used for performance comparisions, which I'll send and include some results, and I'll also try to find a copy of SPECjbb to get results with. -- 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