Re: [PATCH] zram: introduce per-device debug_stat sysfs node

From	Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Newsgroups	linux.kernel
Subject	Re: [PATCH] zram: introduce per-device debug_stat sysfs node
Date	2016-05-13 09:00 +0200
Message-ID	<ryfeN-6kr-5@gated-at.bofh.it> (permalink)
References	<rxBKs-8nL-41@gated-at.bofh.it> <ry8wH-81C-11@gated-at.bofh.it> <ry9M5-XI-7@gated-at.bofh.it> <ryeLR-66n-9@gated-at.bofh.it>
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On (05/13/16 15:23), Minchan Kim wrote:
[..]
> @@ -737,12 +737,12 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
>  		zcomp_strm_release(zram->comp, zstrm);
>  		zstrm = NULL;
>  
> -		atomic64_inc(&zram->stats.num_recompress);
> -
>  		handle = zs_malloc(meta->mem_pool, clen,
>  				GFP_NOIO | __GFP_HIGHMEM);
> -		if (handle)
> +		if (handle) {
> +			atomic64_inc(&zram->stats.num_recompress);
>  			goto compress_again;
> +		}

not like a real concern...

the main (and only) purpose of num_recompress is to match performance
slowdowns and failed fast write paths (when the first zs_malloc() fails).
this matching is depending on successful second zs_malloc(), but if it's
also unsuccessful we would only increase failed_writes; w/o increasing
the failed fast write counter, while we actually would have failed fast
write and extra zs_malloc() [unaccounted in this case]. yet it's probably
a bit unlikely to happen, but still. well, just saying.

	-ss

Thread

Re: [PATCH] zram: introduce per-device debug_stat sysfs node Minchan Kim <minchan@kernel.org> - 2016-05-13 01:50 +0200
  Re: [PATCH] zram: introduce per-device debug_stat sysfs node Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-05-13 03:10 +0200
    Re: [PATCH] zram: introduce per-device debug_stat sysfs node Minchan Kim <minchan@kernel.org> - 2016-05-13 08:30 +0200
      Re: [PATCH] zram: introduce per-device debug_stat sysfs node Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-05-13 09:00 +0200
        Re: [PATCH] zram: introduce per-device debug_stat sysfs node Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-05-13 09:10 +0200
          Re: [PATCH] zram: introduce per-device debug_stat sysfs node Minchan Kim <minchan@kernel.org> - 2016-05-13 09:20 +0200
            Re: [PATCH] zram: introduce per-device debug_stat sysfs node Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-05-13 09:40 +0200
            Re: [PATCH] zram: introduce per-device debug_stat sysfs node Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com> - 2016-05-13 10:10 +0200
              Re: [PATCH] zram: introduce per-device debug_stat sysfs node Minchan Kim <minchan@kernel.org> - 2016-05-14 01:10 +0200
                Re: [PATCH] zram: introduce per-device debug_stat sysfs node Sergey Senozhatsky <sergey.senozhatsky@gmail.com> - 2016-05-14 04:40 +0200

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