Re: [PATCH 0/4] zsmalloc improvements

[Seth Jennings]

On 07/11/2012 02:03 AM, Minchan Kim wrote:
> Today, I tested zsmapbench in my embedded board(ARM).
> tlb-flush is 30% faster than copy-based so it's always not win.
> I think it depends on CPU speed/cache size.

After you pointed this out, I decided to test this on my
Raspberry Pi, the only ARM system I have that is open enough
for me to work with.

I pulled some of the cycle counting stuff out of
arch/arm/kernel/perf_event_v6.c.  I've pushed that code to
the github repo.

git://github.com/spartacus06/zsmapbench.git

My results were in agreement with your findings.  I got 2040
cycles/map for the copy method and 947 cycles/map for the
page-table method.  I think memory speed is playing a big
roll in the difference.

I agree that the page-table method should be restored since
the performance difference is so significant on ARM, a
platform that benefits a lot from memory compression IMHO.

Still, the question remains how to implement the selection
logic, since not all archs that support the page-table
method will necessarily perform better with it.

Thanks,
Seth

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