From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wi0-f175.google.com (mail-wi0-f175.google.com [209.85.212.175]) by kanga.kvack.org (Postfix) with ESMTP id 6598E6B003A for ; Mon, 13 Jan 2014 12:03:26 -0500 (EST) Received: by mail-wi0-f175.google.com with SMTP id hi5so2542177wib.2 for ; Mon, 13 Jan 2014 09:03:25 -0800 (PST) Received: from mail-wi0-x230.google.com (mail-wi0-x230.google.com [2a00:1450:400c:c05::230]) by mx.google.com with ESMTPS id m18si7924802wie.85.2014.01.13.09.03.25 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Mon, 13 Jan 2014 09:03:25 -0800 (PST) Received: by mail-wi0-f176.google.com with SMTP id hq4so2533547wib.3 for ; Mon, 13 Jan 2014 09:03:25 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20140103151154.GA2940@cerebellum.variantweb.net> References: <1387459407-29342-1-git-send-email-ddstreet@ieee.org> <20140103151154.GA2940@cerebellum.variantweb.net> From: Dan Streetman Date: Mon, 13 Jan 2014 12:03:05 -0500 Message-ID: Subject: Re: [PATCH] mm/zswap: add writethrough option Content-Type: text/plain; charset=UTF-8 Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton , Seth Jennings Cc: Linux-MM , linux-kernel , Bob Liu , Minchan Kim , Weijie Yang , Shirish Pargaonkar , Mel Gorman Ping to see if this patch can get picked up. On Fri, Jan 3, 2014 at 10:11 AM, Seth Jennings wrote: > On Thu, Dec 19, 2013 at 08:23:27AM -0500, 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 the >> need for an additional free page (to store the uncompressed page). >> >> This optionally changes zswap to writethrough cache by enabling >> frontswap_writethrough() before registering, so that any >> successful page store will also be written to swap disk. The >> default remains writeback. To enable writethrough, the param >> zswap.writethrough=1 must be used at boot. >> >> Whether writeback or writethrough will provide better performance >> depends on many factors including disk I/O speed/throughput, >> CPU speed(s), system load, etc. In most cases it is likely >> that writeback has better performance than writethrough before >> zswap is full, but after zswap fills up writethrough has >> better performance than writeback. >> >> Signed-off-by: Dan Streetman > > Hey Dan, sorry for the delay on this. Vacation and busyness. > > This looks like a good option for those that don't mind having > the write overhead to ensure that things don't really bog down > if the compress pool overflows, while maintaining the read fault > speedup by decompressing from the pool. > > Acked-by: Seth Jennings -- 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