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Date: Tue, 25 Feb 2014 09:12:52 +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 Tue, Feb 25, 2014 at 02:58:24AM +0300, Sergey Senozhatsky wrote:
> 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
Hmm, I hope we have the abilitiy in the first place because I think
it's not complicate and make test very handy. Please.
>
> 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
> > >
> > > --
> > > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
> > > the body of a message to majordomo@...r.kernel.org
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> > > Please read the FAQ at http://www.tux.org/lkml/
> >
> > --
> > Kind regards,
> > Minchan Kim
> >
> --
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--
Kind regards,
Minchan Kim
--
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