Re: [PATCH 1/1] zram: better utilization of zram swap space

[Sergey Senozhatsky]

On (12/07/17 13:52), Gopi Sai Teja wrote:
> If the length of the compressed page is greater than 75% of the PAGE_SIZE,
> then the page is stored uncompressed in zram space. Zram space utilization
> is improved if the threshold is 80%(5 compressed pages can be stored in
> 4 pages).
> 
> If the compressed length is greater than 3068 and less than 3261, pages
> still can be stored in compressed form in zs_malloc class 3264.
> Currently these compressed pages belong to 4096 zs malloc class.

so this makes sense. I had another idea awhile ago

lkml.kernel.org/r/1456061274-20059-2-git-send-email-sergey.senozhatsky@xxxxxxxxx

in short, 3261 is good, but not as good as it possibly can be. for the
time being, our huge-class watermark starts at 3264. but this can
change.


a side note, I think we have sort of wrong API. zsmalloc knows better which
object is huge. and who knows, may be we will change the number of huge
classes someday or huge-class watermark, etc. so having "hey zsmalloc, is
this object huge or not" API seems to be better than ZRAM's enforcement
"hey zsmalloc, this object is huge".

	-ss