On Sun, Aug 24, 2014 at 8:05 PM, Minchan Kim <minchan@xxxxxxxxxx> wrote: > Normally, zram user could get maximum memory usage zram consumed > via polling mem_used_total with sysfs in userspace. > > But it has a critical problem because user can miss peak memory > usage during update inverval of polling. For avoiding that, > user should poll it with shorter interval(ie, 0.0000000001s) > with mlocking to avoid page fault delay when memory pressure > is heavy. It would be troublesome. > > This patch adds new knob "mem_used_max" so user could see > the maximum memory usage easily via reading the knob and reset > it via "echo 0 > /sys/block/zram0/mem_used_max". > > Reviewed-by: Dan Streetman <ddstreet@xxxxxxxx> Reviewed-by: David Horner <ds2horner@xxxxxxxxx> > Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx> > --- > Documentation/ABI/testing/sysfs-block-zram | 10 +++++ > Documentation/blockdev/zram.txt | 1 + > drivers/block/zram/zram_drv.c | 60 +++++++++++++++++++++++++++++- > drivers/block/zram/zram_drv.h | 1 + > 4 files changed, 70 insertions(+), 2 deletions(-) > > diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram > index dbe643775ec1..01a38eaf1552 100644 > --- a/Documentation/ABI/testing/sysfs-block-zram > +++ b/Documentation/ABI/testing/sysfs-block-zram > @@ -120,6 +120,16 @@ Description: > statistic. > Unit: bytes > > +What: /sys/block/zram<id>/mem_used_max > +Date: August 2014 > +Contact: Minchan Kim <minchan@xxxxxxxxxx> > +Description: > + The mem_used_max file is read/write and specifies the amount > + of maximum memory zram have consumed to store compressed data. > + For resetting the value, you should write "0". Otherwise, > + you could see -EINVAL. > + Unit: bytes > + > What: /sys/block/zram<id>/mem_limit > Date: August 2014 > Contact: Minchan Kim <minchan@xxxxxxxxxx> > diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt > index 82c6a41116db..7fcf9c6592ec 100644 > --- a/Documentation/blockdev/zram.txt > +++ b/Documentation/blockdev/zram.txt > @@ -111,6 +111,7 @@ size of the disk when not in use so a huge zram is wasteful. > orig_data_size > compr_data_size > mem_used_total > + mem_used_max > > 8) Deactivate: > swapoff /dev/zram0 > diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c > index 370c355eb127..1a2b3e320ea5 100644 > --- a/drivers/block/zram/zram_drv.c > +++ b/drivers/block/zram/zram_drv.c > @@ -149,6 +149,41 @@ static ssize_t mem_limit_store(struct device *dev, > return len; > } > > +static ssize_t mem_used_max_show(struct device *dev, > + struct device_attribute *attr, char *buf) > +{ > + u64 val = 0; > + struct zram *zram = dev_to_zram(dev); > + > + down_read(&zram->init_lock); > + if (init_done(zram)) > + val = atomic_long_read(&zram->stats.max_used_pages); > + up_read(&zram->init_lock); > + > + return scnprintf(buf, PAGE_SIZE, "%llu\n", val << PAGE_SHIFT); > +} > + > +static ssize_t mem_used_max_store(struct device *dev, > + struct device_attribute *attr, const char *buf, size_t len) > +{ > + int err; > + unsigned long val; > + struct zram *zram = dev_to_zram(dev); > + struct zram_meta *meta = zram->meta; > + > + err = kstrtoul(buf, 10, &val); > + if (err || val != 0) > + return -EINVAL; > + > + down_read(&zram->init_lock); > + if (init_done(zram)) > + atomic_long_set(&zram->stats.max_used_pages, > + zs_get_total_pages(meta->mem_pool)); > + up_read(&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) > { > @@ -461,6 +496,21 @@ out_cleanup: > return ret; > } > > +static inline void update_used_max(struct zram *zram, > + const unsigned long pages) > +{ > + int old_max, cur_max; > + > + old_max = atomic_long_read(&zram->stats.max_used_pages); > + > + do { > + cur_max = old_max; > + if (pages > cur_max) > + old_max = atomic_long_cmpxchg( > + &zram->stats.max_used_pages, cur_max, pages); > + } while (old_max != cur_max); > +} > + > static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, > int offset) > { > @@ -472,6 +522,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, > struct zram_meta *meta = zram->meta; > struct zcomp_strm *zstrm; > bool locked = false; > + unsigned long alloced_pages; > > page = bvec->bv_page; > if (is_partial_io(bvec)) { > @@ -541,13 +592,15 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, > goto out; > } > > - if (zram->limit_pages && > - zs_get_total_pages(meta->mem_pool) > zram->limit_pages) { > + alloced_pages = zs_get_total_pages(meta->mem_pool); > + if (zram->limit_pages && alloced_pages > zram->limit_pages) { > zs_free(meta->mem_pool, handle); > ret = -ENOMEM; > goto out; > } > > + update_used_max(zram, alloced_pages); > + > cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO); > > if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) { > @@ -897,6 +950,8 @@ 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(mem_used_max, S_IRUGO | S_IWUSR, mem_used_max_show, > + mem_used_max_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, > @@ -926,6 +981,7 @@ static struct attribute *zram_disk_attrs[] = { > &dev_attr_compr_data_size.attr, > &dev_attr_mem_used_total.attr, > &dev_attr_mem_limit.attr, > + &dev_attr_mem_used_max.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 b7aa9c21553f..c6ee271317f5 100644 > --- a/drivers/block/zram/zram_drv.h > +++ b/drivers/block/zram/zram_drv.h > @@ -90,6 +90,7 @@ struct zram_stats { > atomic64_t notify_free; /* no. of swap slot free notifications */ > atomic64_t zero_pages; /* no. of zero filled pages */ > atomic64_t pages_stored; /* no. of pages currently stored */ > + atomic_long_t max_used_pages; /* no. of maximum pages stored */ > }; > > struct zram_meta { > -- > 2.0.0 > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. 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