On Wed, Aug 20, 2014 at 10:20:07PM -0400, David Horner wrote: > On Wed, Aug 20, 2014 at 8:27 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". > > > > 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 | 57 ++++++++++++++++++++++++++++-- > > drivers/block/zram/zram_drv.h | 1 + > > 4 files changed, 67 insertions(+), 2 deletions(-) > > > > diff --git a/Documentation/ABI/testing/sysfs-block-zram b/Documentation/ABI/testing/sysfs-block-zram > > index 025331c19045..ffd1ea7443dd 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 do "echo 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 9f239ff8c444..3b2247c2d4cf 100644 > > --- a/Documentation/blockdev/zram.txt > > +++ b/Documentation/blockdev/zram.txt > > @@ -107,6 +107,7 @@ 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 adc91c7ecaef..138787579478 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 = atomic64_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; > > + > > Yes - this works better for the user than explicit single "0" check > Thanks for testing. > > > + down_read(&zram->init_lock); > > + if (init_done(zram)) > > + atomic64_set(&zram->stats.max_used_pages, > > + zs_get_total_size(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 +496,18 @@ out_cleanup: > > return ret; > > } > > > > +static inline void update_used_max(struct zram *zram, const unsigned long pages) > > +{ > > + u64 old_max, cur_max; > > + > > + do { > > + old_max = cur_max = atomic64_read(&zram->stats.max_used_pages); > > + if (pages > cur_max) > > + old_max = atomic64_cmpxchg(&zram->stats.max_used_pages, > > + cur_max, pages); > > + } while (old_max != cur_max); > > +} > > + > > This can be tightened up some: How many does it make tight? If it's not a big, I'd like to stick my version. > > +static inline void update_used_max(struct zram *zram, const unsigned > long pages) > +{ > + u64 prev_max, old_max = 0; > + > + prev_max = atomic64_read(&zram->stats.max_used_pages); > + do while (pages > prev_max && prev_max != old_max) { > + old_max = prev_max; > + prev_max = atomic64_cmpxchg(&zram->stats.max_used_pages, > + old_max, pages); > + }; > +} > + > > And then can be generalized to: At the moment, we don't need it but it would be good if we need another max in future so I will keep in mind. Thanks for the suggestion! > > > +static inline void update_max(uint64_t *addr, const uint64_t newvalue) > +{ > + uint64_t prev_max, old_max = 0; > + > + prev_max = atomic64_read(addr); > + do while (pages > prev_max && prev_max != old_max) { > + old_max = prev_max; > + prev_max = atomic64_cmpxchg(addr, > + old_max, newvalue); > + }; > +} > + > > > Called with : update_max(&zram->stats.max_used_pages, alloced_pages). > > (I hope I got all the datatypes (I understand there are some implicit > casts) and modes correct). > > The idea should be clear. > > > static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, > > int offset) > > { > > @@ -472,6 +519,7 @@ 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 +589,15 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, > > goto out; > > } > > > > - if (zram->limit_pages && > > - zs_get_total_size(meta->mem_pool) > zram->limit_pages) { > > + alloced_pages = zs_get_total_size(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); > > + > > or generalized with update_max > > > cmem = zs_map_object(meta->mem_pool, handle, ZS_MM_WO); > > > > if ((clen == PAGE_SIZE) && !is_partial_io(bvec)) { > > @@ -897,6 +947,8 @@ 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 +978,7 @@ 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..29383312d543 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 */ > > + atomic64_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. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a> -- Kind regards, Minchan Kim -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>