From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx131.postini.com [74.125.245.131]) by kanga.kvack.org (Postfix) with SMTP id 5ED6C6B0005 for ; Tue, 9 Apr 2013 16:52:51 -0400 (EDT) Received: from /spool/local by e23smtp05.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 10 Apr 2013 06:48:02 +1000 Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [9.190.234.120]) by d23dlp02.au.ibm.com (Postfix) with ESMTP id 805822BB0052 for ; Wed, 10 Apr 2013 06:52:42 +1000 (EST) Received: from d23av01.au.ibm.com (d23av01.au.ibm.com [9.190.234.96]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r39KdNTg11796778 for ; Wed, 10 Apr 2013 06:39:24 +1000 Received: from d23av01.au.ibm.com (loopback [127.0.0.1]) by d23av01.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r39KqeoG007905 for ; Wed, 10 Apr 2013 06:52:41 +1000 Message-ID: <51647F94.6000907@linux.vnet.ibm.com> Date: Tue, 09 Apr 2013 15:52:36 -0500 From: Seth Jennings MIME-Version: 1.0 Subject: Re: zsmalloc defrag (Was: [PATCH] mm: remove compressed copy from zram in-memory) References: <1365400862-9041-1-git-send-email-minchan@kernel.org> <20130409012719.GB3467@blaptop> <20130409013606.GC3467@blaptop> In-Reply-To: <20130409013606.GC3467@blaptop> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Minchan Kim Cc: Dan Magenheimer , Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Hugh Dickins , Nitin Gupta , Konrad Rzeszutek Wilk , Shaohua Li , Bob Liu , Shuah Khan On 04/08/2013 08:36 PM, Minchan Kim wrote: > On Tue, Apr 09, 2013 at 10:27:19AM +0900, Minchan Kim wrote: >> Hi Dan, >> >> On Mon, Apr 08, 2013 at 09:32:38AM -0700, Dan Magenheimer wrote: >>>> From: Minchan Kim [mailto:minchan@kernel.org] >>>> Sent: Monday, April 08, 2013 12:01 AM >>>> Subject: [PATCH] mm: remove compressed copy from zram in-memory >>> >>> (patch removed) >>> >>>> Fragment ratio is almost same but memory consumption and compile time >>>> is better. I am working to add defragment function of zsmalloc. >>> >>> Hi Minchan -- >>> >>> I would be very interested in your design thoughts on >>> how you plan to add defragmentation for zsmalloc. In >> >> What I can say now about is only just a word "Compaction". >> As you know, zsmalloc has a transparent handle so we can do whatever >> under user. Of course, there is a tradeoff between performance >> and memory efficiency. I'm biased to latter for embedded usecase. >> >> And I might post it because as you know well, zsmalloc > > Incomplete sentense, > > I might not post it until promoting zsmalloc because as you know well, > zsmalloc/zram's all new stuffs are blocked into staging tree. > Even if we could add it into staging, as you know well, staging is where > every mm guys ignore so we end up needing another round to promote it. sigh. Yes. The lack of compaction/defragmentation support in zsmalloc has not been raised as an obstacle to mainline acceptance so I think we should wait to add new features to a yet-to-be accepted codebase. Also, I think this feature is more important to zram than it is to zswap/zcache as they can do writeback to free zpages. In other words, the fragmentation is a transient issue for zswap/zcache since writeback to the swap device is possible. Thanks, Seth -- 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