Subject: + zram-factor-out-single-stream-compression.patch added to -mm tree
To: sergey.senozhatsky@xxxxxxxxx,jmarchan@xxxxxxxxxx,minchan@xxxxxxxxxx,ngupta@xxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Fri, 28 Feb 2014 15:52:37 -0800
The patch titled
Subject: zram: factor out single stream compression
has been added to the -mm tree. Its filename is
zram-factor-out-single-stream-compression.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/zram-factor-out-single-stream-compression.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/zram-factor-out-single-stream-compression.patch
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From: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx>
Subject: 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@xxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Jerome Marchand <jmarchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zcomp.c | 62 ++++++++++++++++++++++++++++++-----
drivers/block/zram/zcomp.h | 7 ++-
2 files changed, 59 insertions(+), 10 deletions(-)
diff -puN drivers/block/zram/zcomp.c~zram-factor-out-single-stream-compression drivers/block/zram/zcomp.c
--- a/drivers/block/zram/zcomp.c~zram-factor-out-single-stream-compression
+++ a/drivers/block/zram/zcomp.c
@@ -16,6 +16,14 @@
#include "zcomp.h"
#include "zcomp_lzo.h"
+/*
+ * single zcomp_strm backend
+ */
+struct zcomp_strm_single {
+ struct mutex strm_lock;
+ struct zcomp_strm *zstrm;
+};
+
static struct zcomp_backend *find_backend(const char *compress)
{
if (strncmp(compress, "lzo", 3) == 0)
@@ -54,15 +62,56 @@ static struct zcomp_strm *zcomp_strm_all
return zstrm;
}
+static struct zcomp_strm *zcomp_strm_single_find(struct zcomp *comp)
+{
+ struct zcomp_strm_single *zs = comp->stream;
+ mutex_lock(&zs->strm_lock);
+ return zs->zstrm;
+}
+
+static void zcomp_strm_single_release(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_find = zcomp_strm_single_find;
+ comp->strm_release = zcomp_strm_single_release;
+ 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_find(struct zcomp *comp)
{
- mutex_lock(&comp->strm_lock);
- return comp->zstrm;
+ return comp->strm_find(comp);
}
void zcomp_strm_release(struct zcomp *comp, struct zcomp_strm *zstrm)
{
- mutex_unlock(&comp->strm_lock);
+ comp->strm_release(comp, zstrm);
}
int zcomp_compress(struct zcomp *comp, struct zcomp_strm *zstrm,
@@ -80,7 +129,7 @@ int zcomp_decompress(struct zcomp *comp,
void zcomp_destroy(struct zcomp *comp)
{
- zcomp_strm_free(comp, comp->zstrm);
+ comp->destroy(comp);
kfree(comp);
}
@@ -104,10 +153,7 @@ struct zcomp *zcomp_create(const char *c
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 -puN drivers/block/zram/zcomp.h~zram-factor-out-single-stream-compression drivers/block/zram/zcomp.h
--- a/drivers/block/zram/zcomp.h~zram-factor-out-single-stream-compression
+++ a/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);
_
Patches currently in -mm which might be from sergey.senozhatsky@xxxxxxxxx are
zram-drop-init_done-struct-zram-member.patch
zram-do-not-pass-rw-argument-to-__zram_make_request.patch
zram-remove-good-and-bad-compress-stats.patch
zram-use-atomic64_t-for-all-zram-stats.patch
zram-remove-zram-stats-code-duplication.patch
zram-report-failed-read-and-write-stats.patch
zram-drop-not-used-table-count-member.patch
zram-move-zram-size-warning-to-documentation.patch
zram-document-failed_reads-failed_writes-stats.patch
zram-delete-zram_init_device.patch
zram-introduce-compressing-backend-abstraction.patch
zram-use-zcomp-compressing-backends.patch
zram-factor-out-single-stream-compression.patch
zram-add-multi-stream-functionality.patch
zram-add-set_max_streams-knob.patch
zram-make-compression-algorithm-selection-possible.patch
zram-add-lz4-algorithm-backend.patch
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