Messages in this thread Patch in this message | | | Date | Mon, 2 May 2016 17:06:00 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH 2/2] zram: user per-cpu compression streams |
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On (05/02/16 16:25), Sergey Senozhatsky wrote: [..] > > Trivial: > > We could remove max_strm now and change description. > > oh, yes.
how about something like this? remove max_comp_streams entirely, but leave the attr. if we keep zram->max_comp_streams and return its value (set by user space) from show() handler, we are techically lying; because the actual number of streams is now num_online_cpus().
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From: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> Subject: [PATCH] zram: remove max_comp_streams internals
Remove the internal part of max_comp_streams interface, since we switched to per-cpu streams. We will keep RW max_comp_streams attr around, because:
a) we may (silently) switch back to idle compression streams list and don't want to disturb user space b) max_comp_streams attr must wait for the next 'lay off cycle'; we give user space 2 years to adjust before we remove/downgrade the attr, and there are already several attrs scheduled for removal in 4.11, so it's too late for max_comp_streams.
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> --- drivers/block/zram/zcomp.c | 7 +------ drivers/block/zram/zcomp.h | 2 +- drivers/block/zram/zram_drv.c | 47 +++++++++++-------------------------------- drivers/block/zram/zram_drv.h | 1 - 4 files changed, 14 insertions(+), 43 deletions(-)
diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c index d4159e4..d4de9cb 100644 --- a/drivers/block/zram/zcomp.c +++ b/drivers/block/zram/zcomp.c @@ -95,11 +95,6 @@ bool zcomp_available_algorithm(const char *comp) return find_backend(comp) != NULL; } -bool zcomp_set_max_streams(struct zcomp *comp, int num_strm) -{ - return true; -} - struct zcomp_strm *zcomp_strm_find(struct zcomp *comp) { return *get_cpu_ptr(comp->stream); @@ -211,7 +206,7 @@ void zcomp_destroy(struct zcomp *comp) * case of allocation error, or any other error potentially * returned by functions zcomp_strm_{multi,single}_create. */ -struct zcomp *zcomp_create(const char *compress, int max_strm) +struct zcomp *zcomp_create(const char *compress) { struct zcomp *comp; struct zcomp_backend *backend; diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h index aba8c21..ffd88cb 100644 --- a/drivers/block/zram/zcomp.h +++ b/drivers/block/zram/zcomp.h @@ -45,7 +45,7 @@ struct zcomp { ssize_t zcomp_available_show(const char *comp, char *buf); bool zcomp_available_algorithm(const char *comp); -struct zcomp *zcomp_create(const char *comp, int max_strm); +struct zcomp *zcomp_create(const char *comp); void zcomp_destroy(struct zcomp *comp); struct zcomp_strm *zcomp_strm_find(struct zcomp *comp); diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index cad1751..817e511 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -304,46 +304,25 @@ static ssize_t mem_used_max_store(struct device *dev, return len; } +/* + * We switched to per-cpu streams and this attr is not needed anymore. + * However, we will keep it around for some time, because: + * a) we may revert per-cpu streams in the future + * b) it's visible to user space and we need to follow our 2 years + * retirement rule; but we already have a number of 'soon to be + * altered' attrs, so max_comp_streams need to wait for the next + * layoff cycle. + */ static ssize_t max_comp_streams_show(struct device *dev, struct device_attribute *attr, char *buf) { - int val; - struct zram *zram = dev_to_zram(dev); - - down_read(&zram->init_lock); - val = zram->max_comp_streams; - up_read(&zram->init_lock); - - return scnprintf(buf, PAGE_SIZE, "%d\n", val); + return scnprintf(buf, PAGE_SIZE, "%d\n", num_online_cpus()); } static ssize_t max_comp_streams_store(struct device *dev, struct device_attribute *attr, const char *buf, size_t len) { - int num; - struct zram *zram = dev_to_zram(dev); - int ret; - - ret = kstrtoint(buf, 0, &num); - if (ret < 0) - return ret; - if (num < 1) - return -EINVAL; - - down_write(&zram->init_lock); - if (init_done(zram)) { - if (!zcomp_set_max_streams(zram->comp, num)) { - pr_info("Cannot change max compression streams\n"); - ret = -EINVAL; - goto out; - } - } - - zram->max_comp_streams = num; - ret = len; -out: - up_write(&zram->init_lock); - return ret; + return len; } static ssize_t comp_algorithm_show(struct device *dev, @@ -1035,7 +1014,6 @@ static void zram_reset_device(struct zram *zram) /* Reset stats */ memset(&zram->stats, 0, sizeof(zram->stats)); zram->disksize = 0; - zram->max_comp_streams = 1; set_capacity(zram->disk, 0); part_stat_set_all(&zram->disk->part0, 0); @@ -1064,7 +1042,7 @@ static ssize_t disksize_store(struct device *dev, if (!meta) return -ENOMEM; - comp = zcomp_create(zram->compressor, zram->max_comp_streams); + comp = zcomp_create(zram->compressor); if (IS_ERR(comp)) { pr_err("Cannot initialise %s compressing backend\n", zram->compressor); @@ -1299,7 +1277,6 @@ static int zram_add(void) } strlcpy(zram->compressor, default_compressor, sizeof(zram->compressor)); zram->meta = NULL; - zram->max_comp_streams = 1; pr_info("Added device: %s\n", zram->disk->disk_name); return device_id; diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h index 8e92339..06b1636 100644 --- a/drivers/block/zram/zram_drv.h +++ b/drivers/block/zram/zram_drv.h @@ -102,7 +102,6 @@ struct zram { * the number of pages zram can consume for storing compressed data */ unsigned long limit_pages; - int max_comp_streams; struct zram_stats stats; atomic_t refcount; /* refcount for zram_meta */ -- 2.8.2
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