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Date: Tue, 25 Feb 2014 02:58:24 +0300
From: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To: Minchan Kim <minchan@...nel.org>
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 (02/25/14 08:53), Minchan Kim wrote:
> 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?
>
at the moment (to make it simpler), user can set max stream number
only for un-initialised device. once zcomp created and initialised
user cannot change max streams
pr_info("Can't set max_comp_streams for initialized device\n");
> > +#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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