Re: + zram-support-compaction.patch added to -mm tree

[Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>]

On (03/09/15 09:49), Minchan Kim wrote:
> > rather a discussion question.
> > 
> > Minchan, do you want to provide num_migrated as part of zsmalloc stats rather
> > than having yet another zram attr? we already provide zsmalloc stats and this
> > type of information seems to belong there. just idea.
> 
> Hmm, CONFIG_ZSMALLOC_STAT is actually to show zsmalloc internals.

well, to be fair, compaction is a zsmalloc internal. zram has nothing to do with
it.

but do we we even need this stat? it seems that

   mem_total_used (before compaction) - mem_total_user (after comapction)

will give user an idea on how much memory was compacted.

	-ss

> That's why it is on debugfs. If we add the stat into zsmalloc, we should turn on debugfs
> and CONFIG_ZSMALLOC_STAT to see *a* stat. Even, CONFIG_ZSMALLOC_STAT will add
> unncessary overheads to account another stats fo zsmalloc internals.
> 
> As well, if we add auto-compacion like stuff in zsmalloc(ie, it will trigger
> by itself if fragmention is over to predefined theshold), the stat will
> accumulate stat while someone want to see snapshot compaction effiecieny
> of the moment.
> 
> So, I want to keep it in zram now.
> 
> -- 
> Kind regards,
> Minchan Kim
>