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_get()/zcomp_strm_single_put() get and put compression stream, implement required locking - zcomp_strm_single_create()/zcomp_strm_single_destroy() create and destroy zcomp_strm_single New ->strm_get() and ->strm_put() callbacks added to zcomp, which are set to zcomp_strm_single_get() and zcomp_strm_single_put() during initialisation. Instead of direct locking and zcomp_strm access from zcomp_strm_get() and zcomp_strm_put(), zcomp now calls ->strm_get() and ->strm_put() correspondingly. Signed-off-by: Sergey Senozhatsky <[email protected]> --- drivers/block/zram/zcomp.c | 61 ++++++++++++++++++++++++++++++++++++++++------ drivers/block/zram/zcomp.h | 7 ++++-- 2 files changed, 58 insertions(+), 10 deletions(-) diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c index f67c38a..210cc28 100644 --- a/drivers/block/zram/zcomp.c +++ b/drivers/block/zram/zcomp.c @@ -15,6 +15,14 @@ #include "zcomp.h" +/* + * single zcomp_strm backend + */ +struct zcomp_strm_single { + struct mutex strm_lock; + struct zcomp_strm *zstrm; +}; + extern struct zcomp_backend zcomp_lzo; static struct zcomp_backend *find_backend(const char *compress) @@ -55,15 +63,55 @@ static struct zcomp_strm *zcomp_strm_alloc(struct zcomp *comp) return zstrm; } +static struct zcomp_strm *zcomp_strm_single_get(struct zcomp *comp) +{ + struct zcomp_strm_single *zs = comp->stream; + mutex_lock(&zs->strm_lock); + return zs->zstrm; +} + +static void zcomp_strm_single_put(struct zcomp *comp, struct zcomp_strm *zstrm) +{ + struct zcomp_strm_single *zs = comp->stream; + mutex_unlock(&zs->strm_lock); +} + +static void zcomp_strm_single_destroy(struct zcomp *comp) +{ + struct zcomp_strm_single *zs = comp->stream; + zcomp_strm_free(comp, zs->zstrm); + kfree(zs); +} + +static int zcomp_strm_single_create(struct zcomp *comp) +{ + struct zcomp_strm_single *zs; + + comp->destroy = zcomp_strm_single_destroy; + comp->strm_get = zcomp_strm_single_get; + comp->strm_put = zcomp_strm_single_put; + zs = kmalloc(sizeof(struct zcomp_strm_single), GFP_KERNEL); + if (!zs) + return -ENOMEM; + + comp->stream = zs; + mutex_init(&zs->strm_lock); + zs->zstrm = zcomp_strm_alloc(comp); + if (!zs->zstrm) { + kfree(zs); + return -ENOMEM; + } + return 0; +} + struct zcomp_strm *zcomp_strm_get(struct zcomp *comp) { - mutex_lock(&comp->strm_lock); - return comp->zstrm; + return comp->strm_get(comp); } void zcomp_strm_put(struct zcomp *comp, struct zcomp_strm *zstrm) { - mutex_unlock(&comp->strm_lock); + comp->strm_put(comp, zstrm); } int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm, @@ -81,7 +129,7 @@ int zcomp_decompress(struct zcomp *comp, const unsigned char *src, void zcomp_destroy(struct zcomp *comp) { - zcomp_strm_free(comp, comp->zstrm); + comp->destroy(comp); kfree(comp); } @@ -105,10 +153,7 @@ struct zcomp *zcomp_create(const char *compress) return NULL; comp->backend = backend; - mutex_init(&comp->strm_lock); - - comp->zstrm = zcomp_strm_alloc(comp); - if (!comp->zstrm) { + if (zcomp_strm_single_create(comp) != 0) { kfree(comp); return NULL; } diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h index 5106f8e..861e04d 100644 --- a/drivers/block/zram/zcomp.h +++ b/drivers/block/zram/zcomp.h @@ -34,9 +34,12 @@ 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_get)(struct zcomp *comp); + void (*strm_put)(struct zcomp *comp, struct zcomp_strm *zstrm); + void (*destroy)(struct zcomp *comp); }; struct zcomp *zcomp_create(const char *comp); -- 1.9.0.291.g027825b -- 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/
