From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754683AbbINOO3 (ORCPT ); Mon, 14 Sep 2015 10:14:29 -0400 Received: from mx2.suse.de ([195.135.220.15]:39490 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751300AbbINOO2 (ORCPT ); Mon, 14 Sep 2015 10:14:28 -0400 Subject: Re: [PATCH 0/3] allow zram to use zbud as underlying allocator To: Vitaly Wool References: <20150914154901.92c5b7b24e15f04d8204de18@gmail.com> <55F6D356.5000106@suse.cz> Cc: minchan@kernel.org, sergey.senozhatsky@gmail.com, ddstreet@ieee.org, LKML , linux-mm@kvack.org From: Vlastimil Babka Message-ID: <55F6D641.6010209@suse.cz> Date: Mon, 14 Sep 2015 16:14:25 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.0.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/14/2015 04:12 PM, Vitaly Wool wrote: > On Mon, Sep 14, 2015 at 4:01 PM, Vlastimil Babka wrote: >> >> On 09/14/2015 03:49 PM, Vitaly Wool wrote: >>> >>> While using ZRAM on a small RAM footprint devices, together with >>> KSM, >>> I ran into several occasions when moving pages from compressed swap back >>> into the "normal" part of RAM caused significant latencies in system >> >> >> I'm sure Minchan will want to hear the details of that :) >> >>> operation. By using zbud I lose in compression ratio but gain in >>> determinism, lower latencies and lower fragmentation, so in the coming >> >> >> I doubt the "lower fragmentation" part given what I've read about the design of zbud and zsmalloc? > > As it turns out, I see more cases of compaction kicking in and > significantly more compact_stalls with zsmalloc. Interesting, I thought that zsmalloc doesn't need contiguous high-order pages. > ~vitaly >