From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-f179.google.com (mail-ob0-f179.google.com [209.85.214.179]) by kanga.kvack.org (Postfix) with ESMTP id 087B76B0031 for ; Wed, 20 Nov 2013 19:43:05 -0500 (EST) Received: by mail-ob0-f179.google.com with SMTP id wm4so5607451obc.38 for ; Wed, 20 Nov 2013 16:43:05 -0800 (PST) Received: from aserp1040.oracle.com (aserp1040.oracle.com. [141.146.126.69]) by mx.google.com with ESMTPS id sy1si18122765obc.12.2013.11.20.16.43.04 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Wed, 20 Nov 2013 16:43:04 -0800 (PST) Message-ID: <528D570D.3020006@oracle.com> Date: Thu, 21 Nov 2013 08:42:53 +0800 From: Bob Liu MIME-Version: 1.0 Subject: Re: [PATCH v2] mm/zswap: change zswap to writethrough cache References: <1384976973-32722-1-git-send-email-ddstreet@ieee.org> In-Reply-To: <1384976973-32722-1-git-send-email-ddstreet@ieee.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Dan Streetman Cc: Seth Jennings , linux-mm@kvack.org, linux-kernel , Minchan Kim , Weijie Yang 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. Thanks, -Bob -- 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