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SubjectRe: [PATCH 0/4] zsmalloc improvements
Sorry for not reviewing yet.
By urgent works, I will review this patches on next week.

I hope others can review it.
Thanks.

On 07/03/2012 06:15 AM, Seth Jennings wrote:

> This patchset removes the current x86 dependency for zsmalloc
> and introduces some performance improvements in the object
> mapping paths.
>
> It was meant to be a follow-on to my previous patchest
>
> https://lkml.org/lkml/2012/6/26/540
>
> However, this patchset differed so much in light of new performance
> information that I mostly started over.
>
> In the past, I attempted to compare different mapping methods
> via the use of zcache and frontswap. However, the nature of those
> two features makes comparing mapping method efficiency difficult
> since the mapping is a very small part of the overall code path.
>
> In an effort to get more useful statistics on the mapping speed,
> I wrote a microbenchmark module named zsmapbench, designed to
> measure mapping speed by calling straight into the zsmalloc
> paths.
>
> https://github.com/spartacus06/zsmapbench
>
> This exposed an interesting and unexpected result: in all
> cases that I tried, copying the objects that span pages instead
> of using the page table to map them, was _always_ faster. I could
> not find a case in which the page table mapping method was faster.
>
> zsmapbench measures the copy-based mapping at ~560 cycles for a
> map/unmap operation on spanned object for both KVM guest and bare-metal,
> while the page table mapping was ~1500 cycles on a VM and ~760 cycles
> bare-metal. The cycles for the copy method will vary with
> allocation size, however, it is still faster even for the largest
> allocation that zsmalloc supports.
>
> The result is convenient though, as mempcy is very portable :)
>
> This patchset replaces the x86-only page table mapping code with
> copy-based mapping code. It also makes changes to optimize this
> new method further.
>
> There are no changes in arch/x86 required.
>
> Patchset is based on greg's staging-next.
>
> Seth Jennings (4):
> zsmalloc: remove x86 dependency
> zsmalloc: add single-page object fastpath in unmap
> zsmalloc: add details to zs_map_object boiler plate
> zsmalloc: add mapping modes
>
> drivers/staging/zcache/zcache-main.c | 6 +-
> drivers/staging/zram/zram_drv.c | 7 +-
> drivers/staging/zsmalloc/Kconfig | 4 -
> drivers/staging/zsmalloc/zsmalloc-main.c | 124 ++++++++++++++++++++++--------
> drivers/staging/zsmalloc/zsmalloc.h | 14 +++-
> drivers/staging/zsmalloc/zsmalloc_int.h | 6 +-
> 6 files changed, 114 insertions(+), 47 deletions(-)
>



--
Kind regards,
Minchan Kim


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