The patch titled
Subject: zram: preparation for multi-zcomp support
has been added to the -mm mm-unstable branch. Its filename is
zram-preparation-for-multi-zcomp-support.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/zram-preparation-for-multi-zcomp-support.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Subject: zram: preparation for multi-zcomp support
Date: Wed, 9 Nov 2022 20:50:35 +0900
Patch series "zram: Support multiple compression streams", v5.
This series adds support for multiple compression streams. The main idea
is that different compression algorithms have different characteristics
and zram may benefit when it uses a combination of algorithms: a default
algorithm that is faster but have lower compression rate and a secondary
algorithm that can use higher compression rate at a price of slower
compression/decompression.
There are several use-case for this functionality:
- huge pages re-compression: zstd or deflate can successfully compress
huge pages (~50% of huge pages on my synthetic ChromeOS tests), IOW
pages that lzo was not able to compress.
- idle pages re-compression: idle/cold pages sit in the memory and we
may reduce zsmalloc memory usage if we recompress those idle pages.
Userspace has a number of ways to control the behavior and impact of zram
recompression: what type of pages should be recompressed, size watermarks,
etc. Please refer to documentation patch.
This patch (of 13):
The patch turns compression streams and compressor algorithm name struct
zram members into arrays, so that we can have multiple compression streams
support (in the next patches).
The patch uses a rather explicit API for compressor selection:
- Get primary (default) compression stream
zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP])
- Get secondary compression stream
zcomp_stream_get(zram->comps[ZRAM_SECONDARY_COMP])
We use similar API for compression streams put().
At this point we always have just one compression stream,
since CONFIG_ZRAM_MULTI_COMP is not yet defined.
Link: https://lkml.kernel.org/r/20221109115047.2921851-1-senozhatsky@xxxxxxxxxxxx
Link: https://lkml.kernel.org/r/20221109115047.2921851-2-senozhatsky@xxxxxxxxxxxx
Signed-off-by: Sergey Senozhatsky <senozhatsky@xxxxxxxxxxxx>
Acked-by: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Nitin Gupta <ngupta@xxxxxxxxxx>
Cc: Suleiman Souhlal <suleiman@xxxxxxxxxx>
Cc: Nhat Pham <nphamcs@xxxxxxxxx>
Cc: Alexey Romanov <avromanov@xxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/block/zram/zcomp.c | 6 +-
drivers/block/zram/zcomp.h | 2
drivers/block/zram/zram_drv.c | 90 ++++++++++++++++++++++----------
drivers/block/zram/zram_drv.h | 14 ++++
4 files changed, 80 insertions(+), 32 deletions(-)
--- a/drivers/block/zram/zcomp.c~zram-preparation-for-multi-zcomp-support
+++ a/drivers/block/zram/zcomp.c
@@ -206,7 +206,7 @@ void zcomp_destroy(struct zcomp *comp)
* case of allocation error, or any other error potentially
* returned by zcomp_init().
*/
-struct zcomp *zcomp_create(const char *compress)
+struct zcomp *zcomp_create(const char *alg)
{
struct zcomp *comp;
int error;
@@ -216,14 +216,14 @@ struct zcomp *zcomp_create(const char *c
* is not loaded yet. We must do it here, otherwise we are about to
* call /sbin/modprobe under CPU hot-plug lock.
*/
- if (!zcomp_available_algorithm(compress))
+ if (!zcomp_available_algorithm(alg))
return ERR_PTR(-EINVAL);
comp = kzalloc(sizeof(struct zcomp), GFP_KERNEL);
if (!comp)
return ERR_PTR(-ENOMEM);
- comp->name = compress;
+ comp->name = alg;
error = zcomp_init(comp);
if (error) {
kfree(comp);
--- a/drivers/block/zram/zcomp.h~zram-preparation-for-multi-zcomp-support
+++ a/drivers/block/zram/zcomp.h
@@ -27,7 +27,7 @@ int zcomp_cpu_dead(unsigned int cpu, str
ssize_t zcomp_available_show(const char *comp, char *buf);
bool zcomp_available_algorithm(const char *comp);
-struct zcomp *zcomp_create(const char *comp);
+struct zcomp *zcomp_create(const char *alg);
void zcomp_destroy(struct zcomp *comp);
struct zcomp_strm *zcomp_stream_get(struct zcomp *comp);
--- a/drivers/block/zram/zram_drv.c~zram-preparation-for-multi-zcomp-support
+++ a/drivers/block/zram/zram_drv.c
@@ -1004,36 +1004,53 @@ static ssize_t comp_algorithm_show(struc
struct zram *zram = dev_to_zram(dev);
down_read(&zram->init_lock);
- sz = zcomp_available_show(zram->compressor, buf);
+ sz = zcomp_available_show(zram->comp_algs[ZRAM_PRIMARY_COMP], buf);
up_read(&zram->init_lock);
return sz;
}
+static void comp_algorithm_set(struct zram *zram, u32 prio, const char *alg)
+{
+ /* Do not kfree() algs that we didn't allocate, IOW the default ones */
+ if (zram->comp_algs[prio] != default_compressor)
+ kfree(zram->comp_algs[prio]);
+ zram->comp_algs[prio] = alg;
+}
+
static ssize_t comp_algorithm_store(struct device *dev,
struct device_attribute *attr, const char *buf, size_t len)
{
struct zram *zram = dev_to_zram(dev);
- char compressor[ARRAY_SIZE(zram->compressor)];
+ char *compressor;
size_t sz;
- strscpy(compressor, buf, sizeof(compressor));
+ sz = strlen(buf);
+ if (sz >= CRYPTO_MAX_ALG_NAME)
+ return -E2BIG;
+
+ compressor = kstrdup(buf, GFP_KERNEL);
+ if (!compressor)
+ return -ENOMEM;
+
/* ignore trailing newline */
- sz = strlen(compressor);
if (sz > 0 && compressor[sz - 1] == '\n')
compressor[sz - 1] = 0x00;
- if (!zcomp_available_algorithm(compressor))
+ if (!zcomp_available_algorithm(compressor)) {
+ kfree(compressor);
return -EINVAL;
+ }
down_write(&zram->init_lock);
if (init_done(zram)) {
up_write(&zram->init_lock);
+ kfree(compressor);
pr_info("Can't change algorithm for initialized device\n");
return -EBUSY;
}
- strcpy(zram->compressor, compressor);
+ comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, compressor);
up_write(&zram->init_lock);
return len;
}
@@ -1281,7 +1298,7 @@ static int __zram_bvec_read(struct zram
size = zram_get_obj_size(zram, index);
if (size != PAGE_SIZE)
- zstrm = zcomp_stream_get(zram->comp);
+ zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]);
src = zs_map_object(zram->mem_pool, handle, ZS_MM_RO);
if (size == PAGE_SIZE) {
@@ -1293,7 +1310,7 @@ static int __zram_bvec_read(struct zram
dst = kmap_atomic(page);
ret = zcomp_decompress(zstrm, src, size, dst);
kunmap_atomic(dst);
- zcomp_stream_put(zram->comp);
+ zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]);
}
zs_unmap_object(zram->mem_pool, handle);
zram_slot_unlock(zram, index);
@@ -1360,13 +1377,13 @@ static int __zram_bvec_write(struct zram
kunmap_atomic(mem);
compress_again:
- zstrm = zcomp_stream_get(zram->comp);
+ zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]);
src = kmap_atomic(page);
ret = zcomp_compress(zstrm, src, &comp_len);
kunmap_atomic(src);
if (unlikely(ret)) {
- zcomp_stream_put(zram->comp);
+ zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]);
pr_err("Compression failed! err=%d\n", ret);
zs_free(zram->mem_pool, handle);
return ret;
@@ -1394,7 +1411,7 @@ compress_again:
__GFP_HIGHMEM |
__GFP_MOVABLE);
if (IS_ERR((void *)handle)) {
- zcomp_stream_put(zram->comp);
+ zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]);
atomic64_inc(&zram->stats.writestall);
handle = zs_malloc(zram->mem_pool, comp_len,
GFP_NOIO | __GFP_HIGHMEM |
@@ -1411,14 +1428,14 @@ compress_again:
* zstrm buffer back. It is necessary that the dereferencing
* of the zstrm variable below occurs correctly.
*/
- zstrm = zcomp_stream_get(zram->comp);
+ zstrm = zcomp_stream_get(zram->comps[ZRAM_PRIMARY_COMP]);
}
alloced_pages = zs_get_total_pages(zram->mem_pool);
update_used_max(zram, alloced_pages);
if (zram->limit_pages && alloced_pages > zram->limit_pages) {
- zcomp_stream_put(zram->comp);
+ zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]);
zs_free(zram->mem_pool, handle);
return -ENOMEM;
}
@@ -1432,7 +1449,7 @@ compress_again:
if (comp_len == PAGE_SIZE)
kunmap_atomic(src);
- zcomp_stream_put(zram->comp);
+ zcomp_stream_put(zram->comps[ZRAM_PRIMARY_COMP]);
zs_unmap_object(zram->mem_pool, handle);
atomic64_add(comp_len, &zram->stats.compr_data_size);
out:
@@ -1707,6 +1724,20 @@ out:
return ret;
}
+static void zram_destroy_comps(struct zram *zram)
+{
+ u32 prio;
+
+ for (prio = 0; prio < ZRAM_MAX_COMPS; prio++) {
+ struct zcomp *comp = zram->comps[prio];
+
+ zram->comps[prio] = NULL;
+ if (!comp)
+ continue;
+ zcomp_destroy(comp);
+ }
+}
+
static void zram_reset_device(struct zram *zram)
{
down_write(&zram->init_lock);
@@ -1724,11 +1755,11 @@ static void zram_reset_device(struct zra
/* I/O operation under all of CPU are done so let's free */
zram_meta_free(zram, zram->disksize);
zram->disksize = 0;
+ zram_destroy_comps(zram);
memset(&zram->stats, 0, sizeof(zram->stats));
- zcomp_destroy(zram->comp);
- zram->comp = NULL;
reset_bdev(zram);
+ comp_algorithm_set(zram, ZRAM_PRIMARY_COMP, default_compressor);
up_write(&zram->init_lock);
}
@@ -1739,6 +1770,7 @@ static ssize_t disksize_store(struct dev
struct zcomp *comp;
struct zram *zram = dev_to_zram(dev);
int err;
+ u32 prio;
disksize = memparse(buf, NULL);
if (!disksize)
@@ -1757,22 +1789,28 @@ static ssize_t disksize_store(struct dev
goto out_unlock;
}
- comp = zcomp_create(zram->compressor);
- if (IS_ERR(comp)) {
- pr_err("Cannot initialise %s compressing backend\n",
- zram->compressor);
- err = PTR_ERR(comp);
- goto out_free_meta;
- }
+ for (prio = 0; prio < ZRAM_MAX_COMPS; prio++) {
+ if (!zram->comp_algs[prio])
+ continue;
+
+ comp = zcomp_create(zram->comp_algs[prio]);
+ if (IS_ERR(comp)) {
+ pr_err("Cannot initialise %s compressing backend\n",
+ zram->comp_algs[prio]);
+ err = PTR_ERR(comp);
+ goto out_free_comps;
+ }
- zram->comp = comp;
+ zram->comps[prio] = comp;
+ }
zram->disksize = disksize;
set_capacity_and_notify(zram->disk, zram->disksize >> SECTOR_SHIFT);
up_write(&zram->init_lock);
return len;
-out_free_meta:
+out_free_comps:
+ zram_destroy_comps(zram);
zram_meta_free(zram, disksize);
out_unlock:
up_write(&zram->init_lock);
@@ -1959,7 +1997,7 @@ static int zram_add(void)
if (ret)
goto out_cleanup_disk;
- strscpy(zram->compressor, default_compressor, sizeof(zram->compressor));
+ zram->comp_algs[ZRAM_PRIMARY_COMP] = default_compressor;
zram_debugfs_register(zram);
pr_info("Added device: %s\n", zram->disk->disk_name);
--- a/drivers/block/zram/zram_drv.h~zram-preparation-for-multi-zcomp-support
+++ a/drivers/block/zram/zram_drv.h
@@ -89,10 +89,20 @@ struct zram_stats {
#endif
};
+#ifdef CONFIG_ZRAM_MULTI_COMP
+#define ZRAM_PRIMARY_COMP 0U
+#define ZRAM_SECONDARY_COMP 1U
+#define ZRAM_MAX_COMPS 4U
+#else
+#define ZRAM_PRIMARY_COMP 0U
+#define ZRAM_SECONDARY_COMP 0U
+#define ZRAM_MAX_COMPS 1U
+#endif
+
struct zram {
struct zram_table_entry *table;
struct zs_pool *mem_pool;
- struct zcomp *comp;
+ struct zcomp *comps[ZRAM_MAX_COMPS];
struct gendisk *disk;
/* Prevent concurrent execution of device init */
struct rw_semaphore init_lock;
@@ -107,7 +117,7 @@ struct zram {
* we can store in a disk.
*/
u64 disksize; /* bytes */
- char compressor[CRYPTO_MAX_ALG_NAME];
+ const char *comp_algs[ZRAM_MAX_COMPS];
/*
* zram is claimed so open request will be failed
*/
_
Patches currently in -mm which might be from senozhatsky@xxxxxxxxxxxx are
zram-preparation-for-multi-zcomp-support.patch
zram-add-recompression-algorithm-sysfs-knob.patch
zram-factor-out-wb-and-non-wb-zram-read-functions.patch
zram-introduce-recompress-sysfs-knob.patch
zram-add-recompress-flag-to-read_block_state.patch
zram-clarify-writeback_store-comment.patch
zram-use-is_err_value-to-check-for-zs_malloc-errors.patch
zram-remove-redundant-checks-from-zram_recompress.patch
zram-add-algo-parameter-support-to-zram_recompress.patch
documentation-add-zram-recompression-documentation.patch
zram-add-incompressible-writeback.patch
zram-add-incompressible-flag-to-read_block_state.patch
