Hi Dan,
On Thu, Aug 14, 2014 at 10:33:29AM -0400, Dan Streetman wrote:
> On Wed, Aug 13, 2014 at 8:57 PM, Minchan Kim <minchan@xxxxxxxxxx> wrote:
> > Since zram has no control feature to limit memory usage,
> > it makes hard to manage system memrory.
> >
> > This patch adds new knob "mem_limit" via sysfs to set up the
> > limit.
> >
> > Note: I added the logic in zram, not zsmalloc because the limit
> > is requirement of zram, not zsmalloc so I'd like to avoid
> > unnecessary branch in zsmalloc.
> >
> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
> > ---
> > Documentation/blockdev/zram.txt | 20 +++++++++++++++----
> > drivers/block/zram/zram_drv.c | 43 +++++++++++++++++++++++++++++++++++++++++
> > drivers/block/zram/zram_drv.h | 1 +
> > 3 files changed, 60 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
> > index 0595c3f56ccf..9f239ff8c444 100644
> > --- a/Documentation/blockdev/zram.txt
> > +++ b/Documentation/blockdev/zram.txt
> > @@ -74,14 +74,26 @@ There is little point creating a zram of greater than twice the size of memory
> > since we expect a 2:1 compression ratio. Note that zram uses about 0.1% of the
> > size of the disk when not in use so a huge zram is wasteful.
> >
> > -5) Activate:
> > +5) Set memory limit: Optional
> > + Set memory limit by writing the value to sysfs node 'mem_limit'.
> > + The value can be either in bytes or you can use mem suffixes.
> > + Examples:
> > + # limit /dev/zram0 with 50MB memory
> > + echo $((50*1024*1024)) > /sys/block/zram0/mem_limit
> > +
> > + # Using mem suffixes
> > + echo 256K > /sys/block/zram0/mem_limit
> > + echo 512M > /sys/block/zram0/mem_limit
> > + echo 1G > /sys/block/zram0/mem_limit
> > +
> > +6) Activate:
> > mkswap /dev/zram0
> > swapon /dev/zram0
> >
> > mkfs.ext4 /dev/zram1
> > mount /dev/zram1 /tmp
> >
> > -6) Stats:
> > +7) Stats:
> > Per-device statistics are exported as various nodes under
> > /sys/block/zram<id>/
> > disksize
> > @@ -96,11 +108,11 @@ size of the disk when not in use so a huge zram is wasteful.
> > compr_data_size
> > mem_used_total
> >
> > -7) Deactivate:
> > +8) Deactivate:
> > swapoff /dev/zram0
> > umount /dev/zram1
> >
> > -8) Reset:
> > +9) Reset:
> > Write any positive value to 'reset' sysfs node
> > echo 1 > /sys/block/zram0/reset
> > echo 1 > /sys/block/zram1/reset
> > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c
> > index d00831c3d731..b48a3d0e9031 100644
> > --- a/drivers/block/zram/zram_drv.c
> > +++ b/drivers/block/zram/zram_drv.c
> > @@ -122,6 +122,35 @@ static ssize_t max_comp_streams_show(struct device *dev,
> > return scnprintf(buf, PAGE_SIZE, "%d\n", val);
> > }
> >
> > +static ssize_t mem_limit_show(struct device *dev,
> > + struct device_attribute *attr, char *buf)
> > +{
> > + u64 val;
> > + struct zram *zram = dev_to_zram(dev);
> > +
> > + down_read(&zram->init_lock);
> > + val = zram->limit_bytes;
> > + up_read(&zram->init_lock);
> > +
> > + return scnprintf(buf, PAGE_SIZE, "%llu\n", val);
> > +}
> > +
> > +static ssize_t mem_limit_store(struct device *dev,
> > + struct device_attribute *attr, const char *buf, size_t len)
> > +{
> > + u64 limit;
> > + struct zram *zram = dev_to_zram(dev);
> > +
> > + limit = memparse(buf, NULL);
> > + if (!limit)
> > + return -EINVAL;
>
> Shouldn't passing a 0 limit be allowed, to disable the limit?
Sure. Will fix.
Thanks.
--
Kind regards,
Minchan Kim
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