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author | Sergey Senozhatsky <sergey.senozhatsky@gmail.com> | 2014-04-07 22:38:13 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2014-04-07 23:36:01 (GMT) |
commit | 9cc97529a180b369fcb7e5265771b6ba7e01f05b (patch) | |
tree | c31c25bce7872001d05007d469d035aac15a8276 /drivers/block/zram/zcomp.h | |
parent | b7ca232ee7e85ed3b18e39eb20a7f458ee1d6047 (diff) | |
download | linux-9cc97529a180b369fcb7e5265771b6ba7e01f05b.tar.xz |
zram: factor out single stream compression
This is preparation patch to add multi stream support to zcomp.
Introduce struct zcomp_strm_single and a set of functions to manage
zcomp_strm stream access. zcomp_strm_single implements single compession
stream, same way as current zcomp implementation. This moves zcomp_strm
stream control and locking from zcomp, so compressing backend zcomp is not
aware of required locking.
Single and multi streams require different locking schemes. Minchan Kim
reported that spinlock-based locking scheme (which is used in multi stream
implementation) has demonstrated a severe perfomance regression for single
compression stream case, comparing to mutex-based. see
https://lkml.org/lkml/2014/2/18/16
The following set of functions added:
- zcomp_strm_single_find()/zcomp_strm_single_release()
find and release a compression stream, implement required locking
- zcomp_strm_single_create()/zcomp_strm_single_destroy()
create and destroy zcomp_strm_single
New ->strm_find() and ->strm_release() callbacks added to zcomp, which are
set to zcomp_strm_single_find() and zcomp_strm_single_release() during
initialisation. Instead of direct locking and zcomp_strm access from
zcomp_strm_find() and zcomp_strm_release(), zcomp now calls ->strm_find()
and ->strm_release() correspondingly.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Acked-by: Minchan Kim <minchan@kernel.org>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block/zram/zcomp.h')
-rw-r--r-- | drivers/block/zram/zcomp.h | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h index c9a98e13..dc3500d 100644 --- a/drivers/block/zram/zcomp.h +++ b/drivers/block/zram/zcomp.h @@ -39,9 +39,12 @@ struct zcomp_backend { /* dynamic per-device compression frontend */ struct zcomp { - struct mutex strm_lock; - struct zcomp_strm *zstrm; + void *stream; struct zcomp_backend *backend; + + struct zcomp_strm *(*strm_find)(struct zcomp *comp); + void (*strm_release)(struct zcomp *comp, struct zcomp_strm *zstrm); + void (*destroy)(struct zcomp *comp); }; struct zcomp *zcomp_create(const char *comp); |