On Thu, Mar 12, 2015 at 11:16:09AM +0900, Sergey Senozhatsky wrote: > On (03/12/15 10:55), Minchan Kim wrote: > > I really appreciate you enhance stat functions, esp, working with iostat! > > thanks! my pleasure. > > > One thing I want to discuss is sometime we could remove RO fields > > in /sys/block/zram/ but we couldn't remove RW fields because > > io_stat/mm_stat doesn't have any writable option now so users will > > have two options to read stat. For exmaple, > > I played with CONFIG_ZRAM_OLD_STATS option, which turns RW attrs into > WO attrs (where possible/needed). but it turned out to be a rather > ugly patch and I eventually decided that I don't want to have these > #ifdef-s in zram code for the next two years. so providing both RW/RO > old stats (with a warning in the logs) and RO [mm|io]_stat sound like > a better plan.
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. > > -ss -- Kind regards, Minchan Kim -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
