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

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Fri, Jun 21, 2013 at 08:20:34AM -0700, Dan Magenheimer wrote:
> > From: Bob Liu [mailto:lliubbo@gmail.com]
>  Subject: Re: [PATCHv13 3/4] zswap: add to mm/
> > 
> > On Thu, Jun 20, 2013 at 10:23 PM, Seth Jennings
> > <sjenning@linux.vnet.ibm.com> wrote:
> > > On Thu, Jun 20, 2013 at 05:42:04PM +0800, Bob Liu wrote:
> > >> > Just made a mmtests run of my own and got very different results:
> > >> >
> > >>
> > >> It's strange, I'll update to rc6 and try again.
> > >> By the way, are you using 824 hardware compressor instead of lzo?
> > >
> > > My results where using lzo software compression.
> > >
> > 
> > Thanks, and today I used another machine to test zswap.
> > The total ram size of that machine is around 4G.
> > This time the result is better:
> >                                                rc6                         rc6
> >                                              zswap                        base
> > Ops memcachetest-0M             14619.00 (  0.00%)          15602.00 (  6.72%)
> > Ops memcachetest-435M           14727.00 (  0.00%)          15860.00 (  7.69%)
> > Ops memcachetest-944M           12452.00 (  0.00%)          11812.00 ( -5.14%)
> > Ops memcachetest-1452M          12183.00 (  0.00%)           9829.00 (-19.32%)
> > Ops memcachetest-1961M          11953.00 (  0.00%)           9337.00 (-21.89%)
> > Ops memcachetest-2469M          11201.00 (  0.00%)           7509.00 (-32.96%)
> > Ops memcachetest-2978M           9738.00 (  0.00%)           5981.00 (-38.58%)
> > Ops io-duration-0M                  0.00 (  0.00%)              0.00 (  0.00%)
> > Ops io-duration-435M               10.00 (  0.00%)              6.00 ( 40.00%)
> > Ops io-duration-944M               19.00 (  0.00%)             19.00 (  0.00%)
> > Ops io-duration-1452M              31.00 (  0.00%)             26.00 ( 16.13%)
> > Ops io-duration-1961M              40.00 (  0.00%)             35.00 ( 12.50%)
> > Ops io-duration-2469M              45.00 (  0.00%)             43.00 (  4.44%)
> > Ops io-duration-2978M              58.00 (  0.00%)             53.00 (  8.62%)
> > Ops swaptotal-0M                56711.00 (  0.00%)              8.00 ( 99.99%)
> > Ops swaptotal-435M              19218.00 (  0.00%)           2101.00 ( 89.07%)
> > Ops swaptotal-944M              53233.00 (  0.00%)          98055.00 (-84.20%)
> > Ops swaptotal-1452M             52064.00 (  0.00%)         145624.00 (-179.70%)
> > Ops swaptotal-1961M             54960.00 (  0.00%)         153907.00 (-180.03%)
> > Ops swaptotal-2469M             57485.00 (  0.00%)         176340.00 (-206.76%)
> > Ops swaptotal-2978M             77704.00 (  0.00%)         182996.00 (-135.50%)
> > Ops swapin-0M                   24834.00 (  0.00%)              8.00 ( 99.97%)
> > Ops swapin-435M                  9038.00 (  0.00%)              0.00 (  0.00%)
> > Ops swapin-944M                 26230.00 (  0.00%)          42953.00 (-63.76%)
> > Ops swapin-1452M                25766.00 (  0.00%)          68440.00 (-165.62%)
> > Ops swapin-1961M                27258.00 (  0.00%)          68129.00 (-149.94%)
> > Ops swapin-2469M                28508.00 (  0.00%)          82234.00 (-188.46%)
> > Ops swapin-2978M                37970.00 (  0.00%)          89280.00 (-135.13%)
> > Ops minorfaults-0M            1460163.00 (  0.00%)         927966.00 ( 36.45%)
> > Ops minorfaults-435M           954058.00 (  0.00%)         936182.00 (  1.87%)
> > Ops minorfaults-944M           972818.00 (  0.00%)        1005956.00 ( -3.41%)
> > Ops minorfaults-1452M          966597.00 (  0.00%)        1035465.00 ( -7.12%)
> > Ops minorfaults-1961M          976158.00 (  0.00%)        1049441.00 ( -7.51%)
> > Ops minorfaults-2469M          967815.00 (  0.00%)        1051752.00 ( -8.67%)
> > Ops minorfaults-2978M          988712.00 (  0.00%)        1034615.00 ( -4.64%)
> > Ops majorfaults-0M               5899.00 (  0.00%)              9.00 ( 99.85%)
> > Ops majorfaults-435M             2684.00 (  0.00%)             67.00 ( 97.50%)
> > Ops majorfaults-944M             4380.00 (  0.00%)           5790.00 (-32.19%)
> > Ops majorfaults-1452M            4161.00 (  0.00%)           9222.00 (-121.63%)
> > Ops majorfaults-1961M            4435.00 (  0.00%)           8800.00 (-98.42%)
> > Ops majorfaults-2469M            4555.00 (  0.00%)          10541.00 (-131.42%)
> > Ops majorfaults-2978M            6182.00 (  0.00%)          11618.00 (-87.93%)
> > 
> > 
> > But the performance of the first machine I used whose total ram size
> > is 2G is still bad.
> > I need more time to summarize those testing results.
> > 
> > Maybe you can also have a try with lower total ram size.
> > 
> > --
> > Regards,
> > --Bob
> 
> 
> A very important factor that you are not considering and
> that might account for your different results is the
> "initial conditions".  For example, I always ran my benchmarks
> after a default-configured EL6 boot, which launches many services
> at boot time, each of which creates many anonymous pages,
> and these "service anonymous pages" are often the pages
> that are selected by LRU for swapping, and compressed by zcache/zswap.
> Someone else may run the benchmarks on a minimally-configured
> embedded system, and someone else on a single-user system
> with no services running at all.  A single-user system with
> no services is often best for reproducing benchmark results but
> may not be at all representative of the real world.


Right. And interestingly enough the kernbench recommends
that model so that it is easier to reproduce.

> 
> At a minimum, it would be good to always record "Active(anon)"
> and "Inactive(anon)" in addition to the amount of physical
> RAM in the system.  (Note, in /proc/meminfo on my system,
> the sum of these don't add up to "AnonPages"... I'm not sure
> why.)
> 
> And of course, even if the number of anonymous pages is
> the same, the _contents_ of those pages may be very different,
> which will affect zcache/zswap density which may have
> a large impact on benchmark results.
> 
> Thanks,
> Dan (T-minus two weeks and counting)
> 

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