Messages in this thread | | | Date | Wed, 17 Jul 2013 18:42:18 +0800 | From | Bob Liu <> | Subject | Re: zswap: How to determine whether it is compressing swap pages? |
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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/
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