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Message-ID: <20140224235315.GE24325@bbox>
Date: Tue, 25 Feb 2014 08:53:15 +0900
From: Minchan Kim <minchan@...nel.org>
To: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc: Jerome Marchand <jmarchan@...hat.com>,
Nitin Gupta <ngupta@...are.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCHv6 5/6] zram: enalbe multi stream compression support in
zram
On Fri, Feb 21, 2014 at 02:50:42PM +0300, Sergey Senozhatsky wrote:
> 1) Add ZRAM_MULTI_STREAM configuration option and make multi stream
> zcomp support available.
>
> 2) Introduce zram device attribute max_comp_streams to show and store
> current zcomp's max number of zcomp streams (num_strm).
>
> 3) Extend zcomp zcomp_create() with `num_strm' parameter. `num_strm'
> limits the number of zcomp_strm structs in compression backend's idle
> list (max_comp_streams).
>
> If ZRAM_MULTI_STREAM option selected:
> -- user can change max number of compression streams (max_comp_streams),
> otherwise, attempt to change its default value (1) will be ignored.
> -- passing to zcomp_create() num_strm equals to 1 will initialise zcomp
> using single compression stream zcomp_strm_single (mutex-based locking)
> -- passing to zcomp_create() num_strm greater than 1 will initialise zcomp
> using multi compression stream zcomp_strm_multi (spinlock-based locking)
>
> If ZRAM_MULTI_STREAM has not been selected, only single compression stream
> support available.
>
> iozone -t 3 -R -r 16K -s 60M -I +Z
>
> test base 1 strm (mutex) 3 strm (spinlock)
> -----------------------------------------------------------------------
> Initial write 589286.78 583518.39 718011.05
> Rewrite 604837.97 596776.38 1515125.72
> Random write 584120.11 595714.58 1388850.25
> Pwrite 535731.17 541117.38 739295.27
> Fwrite 1418083.88 1478612.72 1484927.06
>
> Usage example:
> set max_comp_streams to 4
> echo 4 > /sys/block/zram0/max_comp_streams
>
> show current max_comp_streams (default value is 1).
> cat /sys/block/zram0/max_comp_streams
>
> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> ---
> drivers/block/zram/Kconfig | 10 ++++++++++
> drivers/block/zram/zcomp.c | 13 +++++++++++--
> drivers/block/zram/zcomp.h | 2 +-
> drivers/block/zram/zram_drv.c | 43 ++++++++++++++++++++++++++++++++++++++++++-
> drivers/block/zram/zram_drv.h | 2 +-
> 5 files changed, 65 insertions(+), 5 deletions(-)
>
> diff --git a/drivers/block/zram/Kconfig b/drivers/block/zram/Kconfig
> index 3450be8..a2ba9a9 100644
> --- a/drivers/block/zram/Kconfig
> +++ b/drivers/block/zram/Kconfig
> @@ -15,6 +15,16 @@ config ZRAM
>
> See zram.txt for more information.
>
> +config ZRAM_MULTI_STREAM
> + bool "Multi stream compression support"
> + depends on ZRAM
> + default n
> + help
> + This option adds additional functionality to ZRAM, that enables
> + multi compression stream support and provides ability to control
> + maximum number of parallel compressions using max_comp_streams
> + device attribute.
> +
> config ZRAM_DEBUG
> bool "Compressed RAM block device debug support"
> depends on ZRAM
> diff --git a/drivers/block/zram/zcomp.c b/drivers/block/zram/zcomp.c
> index 41325ed..7faa6bd 100644
> --- a/drivers/block/zram/zcomp.c
> +++ b/drivers/block/zram/zcomp.c
> @@ -240,8 +240,9 @@ void zcomp_destroy(struct zcomp *comp)
> * if requested algorithm is not supported or in case
> * of init error
> */
> -struct zcomp *zcomp_create(const char *compress)
> +struct zcomp *zcomp_create(const char *compress, int num_strm)
> {
> + int ret;
> struct zcomp *comp;
> struct zcomp_backend *backend;
>
> @@ -254,7 +255,15 @@ struct zcomp *zcomp_create(const char *compress)
> return NULL;
>
> comp->backend = backend;
> - if (zcomp_strm_single_create(comp) != 0) {
> +#ifdef CONFIG_ZRAM_MULTI_STREAM
> + if (num_strm > 1)
> + ret = zcomp_strm_multi_create(comp, num_strm);
> + else
> + ret = zcomp_strm_single_create(comp);
> +#else
> + ret = zcomp_strm_single_create(comp);
> +#endif
> + if (ret != 0) {
> zcomp_destroy(comp);
> return NULL;
> }
> diff --git a/drivers/block/zram/zcomp.h b/drivers/block/zram/zcomp.h
> index 8dc1d7f..d7e1229 100644
> --- a/drivers/block/zram/zcomp.h
> +++ b/drivers/block/zram/zcomp.h
> @@ -42,7 +42,7 @@ struct zcomp {
> void (*destroy)(struct zcomp *comp);
> };
>
> -struct zcomp *zcomp_create(const char *comp);
> +struct zcomp *zcomp_create(const char *comp, int num_strm);
> void zcomp_destroy(struct zcomp *comp);
>
> struct zcomp_strm *zcomp_strm_get(struct zcomp *comp);
> diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> index 200c12a..c147e6f 100644
> --- a/drivers/block/zram/zram_drv.c
> +++ b/drivers/block/zram/zram_drv.c
> @@ -107,6 +107,42 @@ static ssize_t mem_used_total_show(struct device *dev,
> return sprintf(buf, "%llu\n", val);
> }
>
> +static ssize_t max_comp_streams_show(struct device *dev,
> + struct device_attribute *attr, char *buf)
> +{
> + long val;
Why 'long'?
> + struct zram *zram = dev_to_zram(dev);
> +
> + down_read(&zram->init_lock);
> + val = zram->max_comp_streams;
> + up_read(&zram->init_lock);
> +
> + return sprintf(buf, "%ld\n", val);
> +}
> +
> +static ssize_t max_comp_streams_store(struct device *dev,
> + struct device_attribute *attr, const char *buf, size_t len)
> +{
> +#ifdef CONFIG_ZRAM_MULTI_STREAM
> + long num;
> + struct zram *zram = dev_to_zram(dev);
> +
> + if (kstrtol(buf, 0, &num))
> + return -EINVAL;
> + if (num < 1)
> + return -EINVAL;
> + down_write(&zram->init_lock);
> + if (init_done(zram)) {
> + up_write(&zram->init_lock);
> + pr_info("Can't set max_comp_streams for initialized device\n");
> + return -EBUSY;
> + }
> + zram->max_comp_streams = num;
> + up_write(&zram->init_lock);
If user decrease max stream in runtime, who care of freeing streams?
> +#endif
> + return len;
> +}
> +
> /* flag operations needs meta->tb_lock */
> static int zram_test_flag(struct zram_meta *meta, u32 index,
> enum zram_pageflags flag)
> @@ -503,6 +539,7 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
>
> zcomp_destroy(zram->comp);
> zram->comp = NULL;
> + zram->max_comp_streams = 1;
>
> zram_meta_free(zram->meta);
> zram->meta = NULL;
> @@ -532,7 +569,7 @@ static ssize_t disksize_store(struct device *dev,
> return -EBUSY;
> }
>
> - zram->comp = zcomp_create(default_compressor);
> + zram->comp = zcomp_create(default_compressor, zram->max_comp_streams);
> if (!zram->comp) {
> up_write(&zram->init_lock);
> pr_info("Cannot initialise compressing backend\n");
> @@ -695,6 +732,8 @@ static DEVICE_ATTR(initstate, S_IRUGO, initstate_show, NULL);
> static DEVICE_ATTR(reset, S_IWUSR, NULL, reset_store);
> static DEVICE_ATTR(orig_data_size, S_IRUGO, orig_data_size_show, NULL);
> static DEVICE_ATTR(mem_used_total, S_IRUGO, mem_used_total_show, NULL);
> +static DEVICE_ATTR(max_comp_streams, S_IRUGO | S_IWUSR,
> + max_comp_streams_show, max_comp_streams_store);
>
> ZRAM_ATTR_RO(num_reads);
> ZRAM_ATTR_RO(num_writes);
> @@ -719,6 +758,7 @@ static struct attribute *zram_disk_attrs[] = {
> &dev_attr_orig_data_size.attr,
> &dev_attr_compr_data_size.attr,
> &dev_attr_mem_used_total.attr,
> + &dev_attr_max_comp_streams.attr,
> NULL,
> };
>
> @@ -782,6 +822,7 @@ static int create_device(struct zram *zram, int device_id)
>
> zram->meta = NULL;
> zram->comp = NULL;
> + zram->max_comp_streams = 1;
> return 0;
>
> out_free_disk:
> diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> index 45e04f7..8dccb22 100644
> --- a/drivers/block/zram/zram_drv.h
> +++ b/drivers/block/zram/zram_drv.h
> @@ -99,7 +99,7 @@ struct zram {
> * we can store in a disk.
> */
> u64 disksize; /* bytes */
> -
> + long max_comp_streams;
> struct zram_stats stats;
> };
> #endif
> --
> 1.9.0.291.g027825b
>
> --
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--
Kind regards,
Minchan Kim
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