Re: [PATCH v4 2/4] zram: implement deduplication in zram

[Joonsoo Kim]

On Wed, Apr 26, 2017 at 01:02:43PM +0900, Sergey Senozhatsky wrote:
> On (04/26/17 09:52), js1304@xxxxxxxxx wrote:
> [..]
> > <no-dedup>
> > Elapsed time: out/host: 88 s
> > mm_stat: 8834420736 3658184579 3834208256 0 3834208256 32889 0 0 0
> > 
> > <dedup>
> > Elapsed time: out/host: 100 s
> > mm_stat: 8832929792 3657329322 2832015360 0 2832015360 32609 0 952568877 80880336
> > 
> > It shows performance degradation roughly 13% and save 24% memory. Maybe,
> > it is due to overhead of calculating checksum and comparison.
> 
> I like the patch set, and it makes sense. the benefit is, obviously,
> case-by-case. on my system I've managed to save just 60MB on a 2.7G
> data set, which is far less than I was hoping to save :)
> 
> 
> I usually do DIRECT IO fio performance test. JFYI, the results
> were as follows:

Could you share your fio test setting? I will try to re-generate the
result and analyze it.

I guess that contention happens due to same data page. Could you check
it?

Thanks.