From 461a8eee6af3b55745be64bea403ed0b743563cf Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Thu, 9 Oct 2014 15:29:55 -0700 Subject: [PATCH] zram: report maximum used memory 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 Reviewed-by: Dan Streetman Cc: Sergey Senozhatsky Cc: Jerome Marchand Cc: Cc: Cc: Luigi Semenzato Cc: Nitin Gupta Cc: Seth Jennings Reviewed-by: David Horner Cc: Joonsoo Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- 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 ea67fa3f3cff..b13dc993291f 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/mem_used_max +Date: August 2014 +Contact: Minchan Kim +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/mem_limit Date: August 2014 Contact: Minchan Kim 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 64b27cf9a583..d78b245bae06 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -153,6 +153,41 @@ 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) { @@ -465,6 +500,21 @@ 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) { @@ -476,6 +526,7 @@ 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)) { @@ -545,13 +596,15 @@ 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)) { @@ -901,6 +954,8 @@ 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, @@ -930,6 +985,7 @@ 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 { -- 2.30.2