Messages in this thread | | | Date | Mon, 9 Mar 2015 10:27:28 +0900 | From | Sergey Senozhatsky <> | Subject | Re: + zram-support-compaction.patch added to -mm tree |
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On (03/09/15 10:05), Minchan Kim wrote: > > 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. > > It's not enough. What I want to know is compaction efficiency per client of > zsmalloc(ie, zram). >
so what a typical user can do with this information? isn't it an entirely debug info that makes some hidden sense only to developers?
if you insist on exporting this as a zram stat for everyone how obout starting to move away from per-stat RO sysfs attrs. it seems that we have uncomfortably a lot of sysfs attrs, and that doesn't make life easier in user space. for example, block devices have /sys/block/.../stat file:
/sys/block/sda$ cat stat 45931 59 2075686 289906 55768 9229 1967800 318033 0 193583 607806
and there are no num_reads, num_writes, num_failed_reads, num_failed_writes, etc., etc. per-stat sysfs attrs force user-space to do lots of syscalls: open(), read(), close() with error control on every step; for every stat.
so how about introducing zram<id>/malloc_stats (or any similar name) and provide compaction and all future allocator related stats there (via s*printf("%d %d %d", ....)) ?
-ss
> IOW, (how many of freed pages / how many of objects) per > zs_compact. > > > > > -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 > > > > > -- > Kind regards, > Minchan Kim >
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