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Message-ID: <20140821233658.GH10703@gmail.com>
Date: Thu, 21 Aug 2014 23:36:58 +0000
From: Minchan Kim <minchan@...nel.org>
To: Dan Streetman <ddstreet@...e.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
Linux-MM <linux-mm@...ck.org>,
linux-kernel <linux-kernel@...r.kernel.org>,
Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
Jerome Marchand <jmarchan@...hat.com>, juno.choi@....com,
seungho1.park@....com, Luigi Semenzato <semenzato@...gle.com>,
Nitin Gupta <ngupta@...are.org>,
Seth Jennings <sjennings@...iantweb.net>,
David Horner <ds2horner@...il.com>
Subject: Re: [PATCH v3 3/4] zram: zram memory size limitation
On Thu, Aug 21, 2014 at 03:08:12PM -0400, Dan Streetman wrote:
> On Wed, Aug 20, 2014 at 8:27 PM, Minchan Kim <minchan@...nel.org> 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
> > a limit so that zram could fail allocation once it reaches
> > the limit.
> >
> > Signed-off-by: Minchan Kim <minchan@...nel.org>
> > ---
> > Documentation/ABI/testing/sysfs-block-zram | 9 +++++++
> > Documentation/blockdev/zram.txt | 20 ++++++++++++---
> > drivers/block/zram/zram_drv.c | 41 ++++++++++++++++++++++++++++++
> > drivers/block/zram/zram_drv.h | 5 ++++
> > 4 files changed, 71 insertions(+), 4 deletions(-)
> >
> > diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram
> > index 70ec992514d0..025331c19045 100644
> > --- a/Documentation/ABI/testing/sysfs-block-zram
> > +++ b/Documentation/ABI/testing/sysfs-block-zram
> > @@ -119,3 +119,12 @@ Description:
> > efficiency can be calculated using compr_data_size and this
> > statistic.
> > Unit: bytes
> > +
> > +What: /sys/block/zram<id>/mem_limit
> > +Date: August 2014
> > +Contact: Minchan Kim <minchan@...nel.org>
> > +Description:
> > + The mem_limit file is read/write and specifies the amount
> > + of memory to be able to consume memory to store store
> > + compressed data.
>
> might want to clarify here that the value "0", which is the default,
> disables the limit.
Okay.
>
> > + Unit: bytes
> > 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
>
> # To disable memory limit
> echo 0 > /sys/block/zram0/mem_limit
Yeb.
>
> > +
> > +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 302dd37bcea3..adc91c7ecaef 100644
> > --- a/drivers/block/zram/zram_drv.c
> > +++ b/drivers/block/zram/zram_drv.c
> > @@ -122,6 +122,33 @@ 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_pages;
> > + up_read(&zram->init_lock);
> > +
> > + return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT);
> > +}
> > +
> > +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);
> > + down_write(&zram->init_lock);
> > + zram->limit_pages = PAGE_ALIGN(limit) >> PAGE_SHIFT;
> > + up_write(&zram->init_lock);
> > +
> > + return len;
> > +}
> > +
> > static ssize_t max_comp_streams_store(struct device *dev,
> > struct device_attribute *attr, const char *buf, size_t len)
> > {
> > @@ -513,6 +540,14 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index,
> > ret = -ENOMEM;
> > goto out;
> > }
> > +
> > + if (zram->limit_pages &&
> > + zs_get_total_size(meta->mem_pool) > zram->limit_pages) {
> > + zs_free(meta->mem_pool, handle);
> > + ret = -ENOMEM;
> > + goto out;
> > + }
> > +
> > cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO);
> >
> > if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) {
> > @@ -617,6 +652,9 @@ static void zram_reset_device(struct zram *zram, bool reset_capacity)
> > struct zram_meta *meta;
> >
> > down_write(&zram->init_lock);
> > +
> > + zram->limit_pages = 0;
> > +
> > if (!init_done(zram)) {
> > up_write(&zram->init_lock);
> > return;
> > @@ -857,6 +895,8 @@ 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(mem_limit, S_IRUGO | S_IWUSR, mem_limit_show,
> > + mem_limit_store);
> > static DEVICE_ATTR(max_comp_streams, S_IRUGO | S_IWUSR,
> > max_comp_streams_show, max_comp_streams_store);
> > static DEVICE_ATTR(comp_algorithm, S_IRUGO | S_IWUSR,
> > @@ -885,6 +925,7 @@ 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_mem_limit.attr,
> > &dev_attr_max_comp_streams.attr,
> > &dev_attr_comp_algorithm.attr,
> > NULL,
> > diff --git a/drivers/block/zram/zram_drv.h b/drivers/block/zram/zram_drv.h
> > index e0f725c87cc6..b7aa9c21553f 100644
> > --- a/drivers/block/zram/zram_drv.h
> > +++ b/drivers/block/zram/zram_drv.h
> > @@ -112,6 +112,11 @@ struct zram {
> > u64 disksize; /* bytes */
> > int max_comp_streams;
> > struct zram_stats stats;
> > + /*
> > + * the number of pages zram can consume for storing compressed data
> > + */
> > + unsigned long limit_pages;
> > +
> > char compressor[10];
> > };
> > #endif
> > --
> > 2.0.0
> >
--
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