From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] zram: introduce per-device debug_stat sysfs node
Date: Fri, 13 May 2016 15:58:05 +0900 [thread overview]
Message-ID: <20160513065805.GB615@swordfish> (raw)
In-Reply-To: <20160513062303.GA21204@bbox>
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
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WARNING: multiple messages have this Message-ID (diff)
From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [PATCH] zram: introduce per-device debug_stat sysfs node
Date: Fri, 13 May 2016 15:58:05 +0900 [thread overview]
Message-ID: <20160513065805.GB615@swordfish> (raw)
In-Reply-To: <20160513062303.GA21204@bbox>
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
next prev parent reply other threads:[~2016-05-13 6:58 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-05-11 13:45 [PATCH] zram: introduce per-device debug_stat sysfs node Sergey Senozhatsky
2016-05-11 13:45 ` Sergey Senozhatsky
2016-05-12 23:41 ` Minchan Kim
2016-05-12 23:41 ` Minchan Kim
2016-05-13 1:09 ` Sergey Senozhatsky
2016-05-13 1:09 ` Sergey Senozhatsky
2016-05-13 6:23 ` Minchan Kim
2016-05-13 6:23 ` Minchan Kim
2016-05-13 6:58 ` Sergey Senozhatsky [this message]
2016-05-13 6:58 ` Sergey Senozhatsky
2016-05-13 7:05 ` Sergey Senozhatsky
2016-05-13 7:05 ` Sergey Senozhatsky
2016-05-13 7:20 ` Minchan Kim
2016-05-13 7:20 ` Minchan Kim
2016-05-13 7:41 ` Sergey Senozhatsky
2016-05-13 7:41 ` Sergey Senozhatsky
2016-05-13 8:06 ` Sergey Senozhatsky
2016-05-13 8:06 ` Sergey Senozhatsky
2016-05-13 23:05 ` Minchan Kim
2016-05-13 23:05 ` Minchan Kim
2016-05-14 3:37 ` Sergey Senozhatsky
2016-05-14 3:37 ` Sergey Senozhatsky
-- strict thread matches above, loose matches on Subject: below --
2016-05-13 13:03 Sergey Senozhatsky
2016-05-13 23:08 ` Minchan Kim
2016-05-14 3:38 ` Sergey Senozhatsky
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