Re: [patch] mm: more likely reclaim MADV_SEQUENTIAL mappings II

[Johannes Weiner <hannes@saeurebad.de>]

Johannes Weiner <hannes@saeurebad.de> writes:

> Rik van Riel <riel@redhat.com> writes:
>
>> KOSAKI Motohiro wrote:
>>>> mmotm:
>>>>     normal  user: 1.775000s [0.053307] system: 9.620000s [0.135339] total: 98.875000s [0.613956]
>>>>    madvise  user: 2.552500s [0.041307] system: 9.442500s [0.075980] total: 73.937500s [0.734170]
>>>> mmotm+patch:
>>>>     normal  user: 1.850000s [0.013540] system: 9.760000s [0.047081] total: 99.250000s [0.569386]
>>>>    madvise  user: 2.547500s [0.014930] system: 8.865000s [0.055000] total: 71.897500s [0.144763]
>>>>
>>>> Well, time-wise not sooo much of an improvement.  But given the
>>>> massively decreased LRU-rotation [ http://hannes.saeurebad.de/madvseq/ ]
>>>
>>> My first impression, this result mean the patch is not so useful.
>>> But anyway, I mesured it again because I think Nick's opinion is very
>>> reasonable and I don't know your mesurement condition so detail.
>>
>> It may not make much of a difference if the MADV_SEQUENTIAL
>> program is the only thing running on the system.
>
> As said, I had a big dd running in the background.  The box has only
> 768mb RAM, so there really was VM activity going on.
>
> And given this small standard deviations, the numbers seem pretty
> stable.  Even if I had taken more samples, I highly doubt that they
> would have looked much different.
>
> Perhaps still not enough VM pressure...

Okay, Rik was kind enough to explain me what was wrong about my approach
on IRC.

Yes, the benchmark pretty much missed the point.  Please ignore.

        Hannes

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