diff options
author | Minchan Kim <minchan@kernel.org> | 2018-12-28 00:36:54 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2018-12-28 12:11:49 -0800 |
commit | bb416d18b850faaa44bd3bb67c9728922c3cce98 (patch) | |
tree | 112f74c2842e9e2565911546cb0ff69c407ad393 /drivers/block/zram/zram_drv.c | |
parent | 23eddf39b2c28c05cb8f8203d38e61807d701b38 (diff) | |
download | linux-bb416d18b850faaa44bd3bb67c9728922c3cce98.tar.bz2 |
zram: writeback throttle
If there are lots of write IO with flash device, it could have a
wearout problem of storage. To overcome the problem, admin needs
to design write limitation to guarantee flash health
for entire product life.
This patch creates a new knob "writeback_limit" for zram.
writeback_limit's default value is 0 so that it doesn't limit
any writeback. If admin want to measure writeback count in a
certain period, he could know it via /sys/block/zram0/bd_stat's
3rd column.
If admin want to limit writeback as per-day 400M, he could do it
like below.
MB_SHIFT=20
4K_SHIFT=12
echo $((400<<MB_SHIFT>>4K_SHIFT)) > \
/sys/block/zram0/writeback_limit.
If admin want to allow further write again, he could do it like below
echo 0 > /sys/block/zram0/writeback_limit
If admin want to see remaining writeback budget,
cat /sys/block/zram0/writeback_limit
The writeback_limit count will reset whenever you reset zram (e.g., system
reboot, echo 1 > /sys/block/zramX/reset) so keeping how many of writeback
happened until you reset the zram to allocate extra writeback budget in
next setting is user's job.
[minchan@kernel.org: v4]
Link: http://lkml.kernel.org/r/20181203024045.153534-8-minchan@kernel.org
Link: http://lkml.kernel.org/r/20181127055429.251614-8-minchan@kernel.org
Signed-off-by: Minchan Kim <minchan@kernel.org>
Reviewed-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Joey Pabalinas <joeypabalinas@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'drivers/block/zram/zram_drv.c')
-rw-r--r-- | drivers/block/zram/zram_drv.c | 52 |
1 files changed, 49 insertions, 3 deletions
diff --git a/drivers/block/zram/zram_drv.c b/drivers/block/zram/zram_drv.c index f1832fa3ba41..33c5cc879f24 100644 --- a/drivers/block/zram/zram_drv.c +++ b/drivers/block/zram/zram_drv.c @@ -330,6 +330,39 @@ next: } #ifdef CONFIG_ZRAM_WRITEBACK +static ssize_t writeback_limit_store(struct device *dev, + struct device_attribute *attr, const char *buf, size_t len) +{ + struct zram *zram = dev_to_zram(dev); + u64 val; + ssize_t ret = -EINVAL; + + if (kstrtoull(buf, 10, &val)) + return ret; + + down_read(&zram->init_lock); + atomic64_set(&zram->stats.bd_wb_limit, val); + if (val == 0) + zram->stop_writeback = false; + up_read(&zram->init_lock); + ret = len; + + return ret; +} + +static ssize_t writeback_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 = atomic64_read(&zram->stats.bd_wb_limit); + up_read(&zram->init_lock); + + return scnprintf(buf, PAGE_SIZE, "%llu\n", val); +} + static void reset_bdev(struct zram *zram) { struct block_device *bdev; @@ -612,6 +645,11 @@ static ssize_t writeback_store(struct device *dev, bvec.bv_len = PAGE_SIZE; bvec.bv_offset = 0; + if (zram->stop_writeback) { + ret = -EIO; + break; + } + if (!blk_idx) { blk_idx = alloc_block_bdev(zram); if (!blk_idx) { @@ -694,6 +732,11 @@ static ssize_t writeback_store(struct device *dev, zram_set_element(zram, index, blk_idx); blk_idx = 0; atomic64_inc(&zram->stats.pages_stored); + if (atomic64_add_unless(&zram->stats.bd_wb_limit, + -1 << (PAGE_SHIFT - 12), 0)) { + if (atomic64_read(&zram->stats.bd_wb_limit) == 0) + zram->stop_writeback = true; + } next: zram_slot_unlock(zram, index); } @@ -1018,6 +1061,7 @@ static ssize_t mm_stat_show(struct device *dev, } #ifdef CONFIG_ZRAM_WRITEBACK +#define FOUR_K(x) ((x) * (1 << (PAGE_SHIFT - 12))) static ssize_t bd_stat_show(struct device *dev, struct device_attribute *attr, char *buf) { @@ -1027,9 +1071,9 @@ static ssize_t bd_stat_show(struct device *dev, down_read(&zram->init_lock); ret = scnprintf(buf, PAGE_SIZE, "%8llu %8llu %8llu\n", - (u64)atomic64_read(&zram->stats.bd_count) * (PAGE_SHIFT - 12), - (u64)atomic64_read(&zram->stats.bd_reads) * (PAGE_SHIFT - 12), - (u64)atomic64_read(&zram->stats.bd_writes) * (PAGE_SHIFT - 12)); + FOUR_K((u64)atomic64_read(&zram->stats.bd_count)), + FOUR_K((u64)atomic64_read(&zram->stats.bd_reads)), + FOUR_K((u64)atomic64_read(&zram->stats.bd_writes))); up_read(&zram->init_lock); return ret; @@ -1767,6 +1811,7 @@ static DEVICE_ATTR_RW(comp_algorithm); #ifdef CONFIG_ZRAM_WRITEBACK static DEVICE_ATTR_RW(backing_dev); static DEVICE_ATTR_WO(writeback); +static DEVICE_ATTR_RW(writeback_limit); #endif static struct attribute *zram_disk_attrs[] = { @@ -1782,6 +1827,7 @@ static struct attribute *zram_disk_attrs[] = { #ifdef CONFIG_ZRAM_WRITEBACK &dev_attr_backing_dev.attr, &dev_attr_writeback.attr, + &dev_attr_writeback_limit.attr, #endif &dev_attr_io_stat.attr, &dev_attr_mm_stat.attr, |