Re: [PATCH 0/6] new zram statistics reporting scheme

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

On (03/12/15 14:11), Minchan Kim wrote:
> I think we don't need CONFIG_ZRAM_OLD_STATS.
> For example, for mem_used_max, we could add pr_warn_once in
> *mem_used_max_show* but not *mem_used_max_store*. so, old users will see
> deprecated message when they try to *read* the vaule old stat while they
> will write new value.
> One or two year later, we could remove mem_used_max_show then everyone
> should read the vaule /sys/block/zram0/mm_stat.
> 
> > 
> > >         cat /sys/block/zram/mem_used_max
> > >         cat /sys/block/zram/mm_stat | awk friend
> > > 
> > > How about changing only writeable, not readable for duplicated stats
> > > in /sys/block/zram? So, user will have writeable stat to set some
> > > options in /sys/block/zram and readable stat to get some data in
> > > /sys/block/zram/[io|mm]_stat if the stat is duplicated in both.
> > 
> > Sorry, I probably didn't drink enough coffee today, can you please
> > rephrase or give a trivial example?
> 
> Sorry, I was vague. I meant users can read the vaule for
> mem_used_max and mem_limit in two places(ie, /sys/block/zram/
> and /sys/block/zram/mm_stat). If we feel it's handy for user,
> i am not against that. But if there is no reason, I want to
> make /sys/block/zram/ stat write-only if it is possible stat
> like mem_used_max. I guess It's easier rule for user.

in a long term -- yes. duplication must go away. we provide [mm|io]_stat
nodes to do stats show.

so,
-- RW will be downgraded to WO
-- RO will be removed

(I'm talking about those attrs that are currently visible in two
places -- the original per-stat sysfs node and new [mm|io]_stat node).


and this is what CONFIG_ZRAM_OLD_STATS was doing: downgrade of RW to WO,
removal of some RO attrs. but I'd prefer to go with warn once plan and
do this downgrade/removal manually two years later.

	-ss