Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753604Ab3GQKmb (ORCPT ); Wed, 17 Jul 2013 06:42:31 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:49667 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753000Ab3GQKma (ORCPT ); Wed, 17 Jul 2013 06:42:30 -0400 Message-ID: <51E6750A.9060900@oracle.com> Date: Wed, 17 Jul 2013 18:42:18 +0800 From: Bob Liu User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130221 Thunderbird/17.0.3 MIME-Version: 1.0 To: Martin Steigerwald CC: Seth Jennings , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: zswap: How to determine whether it is compressing swap pages? References: <1674223.HVFdAhB7u5@merkaba> In-Reply-To: <1674223.HVFdAhB7u5@merkaba> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Source-IP: ucsinet21.oracle.com [156.151.31.93] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3774 Lines: 121 Hi Martin, On 07/17/2013 06:04 PM, Martin Steigerwald wrote: > Hi Seth, hi everyone, > > Yesterday I build 3.11-rc1 with CONFIG_ZSWAP and wanted to test it. > > I added zswap.enabled=1 and get: > > martin@merkaba:~> dmesg | grep zswap > [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-3.11.0-rc1-tp520+ > root=/dev/mapper/merkaba-debian ro rootflags=subvol=root init=/bin/systemd > cgroup_enable=memory threadirqs i915.i915_enable_rc6=7 zcache zswap.enabled=1 > [ 0.000000] Kernel command line: BOOT_IMAGE=/vmlinuz-3.11.0-rc1-tp520+ > root=/dev/mapper/merkaba-debian ro rootflags=subvol=root init=/bin/systemd > cgroup_enable=memory threadirqs i915.i915_enable_rc6=7 zcache zswap.enabled=1 > [ 1.452443] zswap: loading zswap > [ 1.452465] zswap: using lzo compressor > > > I did a stress -m 1 --vm-keep --vm-bytes 4G on this 8 GB ThinkPad T520 in > order to allocate some swap. > Thank you for your testing. I'm glad to see there is new people interested with memory compression. > Still I think zswap didn?t do anything: > > merkaba:/sys/kernel/debug/zswap> grep . * > duplicate_entry:0 > pool_limit_hit:0 > pool_pages:0 > reject_alloc_fail:0 > reject_compress_poor:0 > reject_kmemcache_fail:0 > reject_reclaim_fail:0 > stored_pages:0 > written_back_pages:0 > > > However: > > merkaba:/sys/kernel/slab/zswap_entry> grep . * > aliases:9 > align:8 > grep: alloc_calls: Die angeforderte Funktion ist nicht implementiert > cache_dma:0 > cpu_partial:0 > cpu_slabs:4 N0=4 > destroy_by_rcu:0 > grep: free_calls: Die angeforderte Funktion ist nicht implementiert > hwcache_align:0 > min_partial:5 > objects:2550 N0=2550 > object_size:48 > objects_partial:0 > objs_per_slab:85 > order:0 > partial:0 > poison:0 > reclaim_account:0 > red_zone:0 > remote_node_defrag_ratio:100 > reserved:0 > sanity_checks:0 > slabs:30 N0=30 > slabs_cpu_partial:0(0) > slab_size:48 > store_user:0 > total_objects:2550 N0=2550 > trace:0 > > It has some objects it seems. > > > How do I know whether zswap actually does something? > > Will zswap work even with zcache enabled? As I understand zcache compresses > swap device pages on the block device level in addition to compressing read > cache pages of usual filesystems. Which one takes precedence, zcache or zswap? > Can I disable zcache for swap device? > Please disable zcache and try again. > > > Here is dmesg for zcache: > > martin@merkaba:~> dmesg | grep zcache > [ 0.000000] Command line: BOOT_IMAGE=/vmlinuz-3.11.0-rc1-tp520+ > root=/dev/mapper/merkaba-debian ro rootflags=subvol=root init=/bin/systemd > cgroup_enable=memory threadirqs i915.i915_enable_rc6=7 zcache zswap.enabled=1 > [ 0.000000] Kernel command line: BOOT_IMAGE=/vmlinuz-3.11.0-rc1-tp520+ > root=/dev/mapper/merkaba-debian ro rootflags=subvol=root init=/bin/systemd > cgroup_enable=memory threadirqs i915.i915_enable_rc6=7 zcache zswap.enabled=1 > [ 1.453531] zcache: using lzo compressor > [ 1.453634] zcache: cleancache enabled using kernel transcendent memory and > compression buddies > [ 1.453679] zcache: frontswap enabled using kernel transcendent memory and > compression buddies > [ 1.453722] zcache: frontswap_ops overridden > [ 5.358288] zcache: created ephemeral local tmem pool, id=0 > [ 8.155684] zcache: created persistent local tmem pool, id=1 > [ 8.331680] zcache: created ephemeral local tmem pool, id=2 > [ 8.593235] zcache: created ephemeral local tmem pool, id=3 > [ 8.743330] zcache: created ephemeral local tmem pool, id=4 > > > Thanks, > -- Regards, -Bob -- 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/