From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa0-f47.google.com (mail-oa0-f47.google.com [209.85.219.47]) by kanga.kvack.org (Postfix) with ESMTP id ADF326B0031 for ; Mon, 23 Sep 2013 13:40:45 -0400 (EDT) Received: by mail-oa0-f47.google.com with SMTP id i1so863456oag.34 for ; Mon, 23 Sep 2013 10:40:45 -0700 (PDT) Received: from /spool/local by e9.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 23 Sep 2013 13:20:24 -0400 Received: from b01cxnp23032.gho.pok.ibm.com (b01cxnp23032.gho.pok.ibm.com [9.57.198.27]) by d01dlp01.pok.ibm.com (Postfix) with ESMTP id 429B138C803B for ; Mon, 23 Sep 2013 13:20:22 -0400 (EDT) Received: from d01av01.pok.ibm.com (d01av01.pok.ibm.com [9.56.224.215]) by b01cxnp23032.gho.pok.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r8NHKMn462390386 for ; Mon, 23 Sep 2013 17:20:22 GMT Received: from d01av01.pok.ibm.com (loopback [127.0.0.1]) by d01av01.pok.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r8NHJLnx003172 for ; Mon, 23 Sep 2013 13:19:21 -0400 Date: Mon, 23 Sep 2013 12:19:16 -0500 From: Seth Jennings Subject: Re: [PATCH v2 0/5] mm: migrate zbud pages Message-ID: <20130923171916.GA23643@variantweb.net> References: <1378889944-23192-1-git-send-email-k.kozlowski@samsung.com> <5237FDCC.5010109@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5237FDCC.5010109@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Bob Liu Cc: Krzysztof Kozlowski , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton , Mel Gorman , Bartlomiej Zolnierkiewicz , Marek Szyprowski , Kyungmin Park , Dave Hansen , Minchan Kim On Tue, Sep 17, 2013 at 02:59:24PM +0800, Bob Liu wrote: > Hi Krzysztof, > > On 09/11/2013 04:58 PM, Krzysztof Kozlowski wrote: > > Hi, > > > > Currently zbud pages are not movable and they cannot be allocated from CMA > > (Contiguous Memory Allocator) region. These patches add migration of zbud pages. > > > > I agree that the migration of zbud pages is important so that system > will not enter order-0 page fragmentation and can be helpful for page > compaction/huge pages etc.. > > But after I looked at the [patch 4/5], I found it will make zbud very > complicated. > I'd prefer to add this migration feature later until current version > zswap/zbud becomes better enough and more stable. I agree with this. We are also looking to add zsmalloc as an option too. It would be nice to come up with a solution that worked for both (any) allocator that zswap used. > > Mel mentioned several problems about zswap/zbud in thread "[PATCH v6 > 0/5] zram/zsmalloc promotion". > > Like "it's clunky as hell and the layering between zswap and zbud is > twisty" and "I think I brought up its stalling behaviour during review > when it was being merged. It would have been preferable if writeback > could be initiated in batches and then waited on at the very least.. > It's worse that it uses _swap_writepage directly instead of going > through a writepage ops. It would have been better if zbud pages > existed on the LRU and written back with an address space ops and > properly handled asynchonous writeback." Yes, the laying in zswap vs zbud is wonky and should be addressed before adding new layers. > > So I think it would be better if we can address those issues at first > and it would be easier to address these issues before adding more new > features. Welcome any ideas. Agreed. 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