Re: [PATCHv13 3/4] zswap: add to mm/

From: Bob Liu
Date: Mon Jun 17 2013 - 02:20:15 EST


Hi Seth,

On Tue, Jun 4, 2013 at 4:33 AM, Seth Jennings
<sjenning@xxxxxxxxxxxxxxxxxx> wrote:
> zswap is a thin backend for frontswap that takes pages that are in the process
> of being swapped out and attempts to compress them and store them in a
> RAM-based memory pool. This can result in a significant I/O reduction on the
> swap device and, in the case where decompressing from RAM is faster than
> reading from the swap device, can also improve workload performance.
>
> It also has support for evicting swap pages that are currently compressed in
> zswap to the swap device on an LRU(ish) basis. This functionality makes zswap a
> true cache in that, once the cache is full, the oldest pages can be moved out
> of zswap to the swap device so newer pages can be compressed and stored in
> zswap.
>
> This patch adds the zswap driver to mm/
>

Do you have any more benchmark can share with me ? To figure out that
we can benefit from zswap.

I found zswap will cause performance drop when using mmtests-0.10 to test it.
The config file I'm using is: config-global-dhp__parallelio-memcachetest

The result is:
(v3.10-rc4-2G-nozswap was without zswap but the performance is better.)

v3.10-rc4 v3.10-rc4
2G-zswap-base 2G-nozswap
Ops memcachetest-0M 604.00 ( 0.00%) 1077.00 ( 78.31%)
Ops memcachetest-198M 630.00 ( 0.00%) 1007.00 ( 59.84%)
Ops memcachetest-430M 609.00 ( 0.00%) 939.00 ( 54.19%)
Ops memcachetest-661M 604.00 ( 0.00%) 845.00 ( 39.90%)
Ops memcachetest-893M 591.00 ( 0.00%) 839.00 ( 41.96%)
Ops memcachetest-1125M 599.00 ( 0.00%) 781.00 ( 30.38%)
Ops memcachetest-1356M 588.00 ( 0.00%) 771.00 ( 31.12%)
Ops io-duration-0M 0.00 ( 0.00%) 1.00 (-99.00%)
Ops io-duration-198M 177.00 ( 0.00%) 21.00 ( 88.14%)
Ops io-duration-430M 168.00 ( 0.00%) 25.00 ( 85.12%)
Ops io-duration-661M 214.00 ( 0.00%) 30.00 ( 85.98%)
Ops io-duration-893M 186.00 ( 0.00%) 32.00 ( 82.80%)
Ops io-duration-1125M 175.00 ( 0.00%) 42.00 ( 76.00%)
Ops io-duration-1356M 245.00 ( 0.00%) 51.00 ( 79.18%)
Ops swaptotal-0M 487760.00 ( 0.00%) 459754.00 ( 5.74%)
Ops swaptotal-198M 563581.00 ( 0.00%) 485194.00 ( 13.91%)
Ops swaptotal-430M 579472.00 ( 0.00%) 500817.00 ( 13.57%)
Ops swaptotal-661M 568086.00 ( 0.00%) 524209.00 ( 7.72%)
Ops swaptotal-893M 584405.00 ( 0.00%) 509846.00 ( 12.76%)
Ops swaptotal-1125M 572992.00 ( 0.00%) 534115.00 ( 6.78%)
Ops swaptotal-1356M 573259.00 ( 0.00%) 529814.00 ( 7.58%)
Ops swapin-0M 231250.00 ( 0.00%) 236069.00 ( -2.08%)
Ops swapin-198M 312259.00 ( 0.00%) 239149.00 ( 23.41%)
Ops swapin-430M 327178.00 ( 0.00%) 246803.00 ( 24.57%)
Ops swapin-661M 319575.00 ( 0.00%) 273644.00 ( 14.37%)
Ops swapin-893M 328195.00 ( 0.00%) 257327.00 ( 21.59%)
Ops swapin-1125M 317345.00 ( 0.00%) 271109.00 ( 14.57%)
Ops swapin-1356M 312858.00 ( 0.00%) 266050.00 ( 14.96%)
Ops minorfaults-0M 592150.00 ( 0.00%) 646076.00 ( -9.11%)
Ops minorfaults-198M 637339.00 ( 0.00%) 676441.00 ( -6.14%)
Ops minorfaults-430M 626228.00 ( 0.00%) 684715.00 ( -9.34%)
Ops minorfaults-661M 625089.00 ( 0.00%) 670639.00 ( -7.29%)
Ops minorfaults-893M 612877.00 ( 0.00%) 669723.00 ( -9.28%)
Ops minorfaults-1125M 624800.00 ( 0.00%) 667025.00 ( -6.76%)
Ops minorfaults-1356M 618800.00 ( 0.00%) 657600.00 ( -6.27%)
Ops majorfaults-0M 67664.00 ( 0.00%) 40060.00 ( 40.80%)
Ops majorfaults-198M 72377.00 ( 0.00%) 39517.00 ( 45.40%)
Ops majorfaults-430M 71822.00 ( 0.00%) 38895.00 ( 45.85%)
Ops majorfaults-661M 70009.00 ( 0.00%) 39625.00 ( 43.40%)
Ops majorfaults-893M 74988.00 ( 0.00%) 38073.00 ( 49.23%)
Ops majorfaults-1125M 72458.00 ( 0.00%) 38206.00 ( 47.27%)
Ops majorfaults-1356M 70549.00 ( 0.00%) 37430.00 ( 46.94%)

Regards,
-Bob
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