Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S936388Ab3DIUwt (ORCPT ); Tue, 9 Apr 2013 16:52:49 -0400 Received: from e23smtp04.au.ibm.com ([202.81.31.146]:50967 "EHLO e23smtp04.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936140Ab3DIUws (ORCPT ); Tue, 9 Apr 2013 16:52:48 -0400 Message-ID: <51647F94.6000907@linux.vnet.ibm.com> Date: Tue, 09 Apr 2013 15:52:36 -0500 From: Seth Jennings User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 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 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 X-Content-Scanned: Fidelis XPS MAILER x-cbid: 13040920-9264-0000-0000-0000037C339A Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2025 Lines: 50 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 from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/