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Diffstat (limited to 'Documentation/blockdev/zram.txt')
| -rw-r--r-- | Documentation/blockdev/zram.txt | 87 |
1 files changed, 73 insertions, 14 deletions
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt index 7fcf9c6592ec..48a183e29988 100644 --- a/Documentation/blockdev/zram.txt +++ b/Documentation/blockdev/zram.txt @@ -98,20 +98,79 @@ size of the disk when not in use so a huge zram is wasteful. mount /dev/zram1 /tmp 7) Stats: - Per-device statistics are exported as various nodes under - /sys/block/zram<id>/ - disksize - num_reads - num_writes - failed_reads - failed_writes - invalid_io - notify_free - zero_pages - orig_data_size - compr_data_size - mem_used_total - mem_used_max +Per-device statistics are exported as various nodes under /sys/block/zram<id>/ + +A brief description of exported device attritbutes. For more details please +read Documentation/ABI/testing/sysfs-block-zram. + +Name access description +---- ------ ----------- +disksize RW show and set the device's disk size +initstate RO shows the initialization state of the device +reset WO trigger device reset +num_reads RO the number of reads +failed_reads RO the number of failed reads +num_write RO the number of writes +failed_writes RO the number of failed writes +invalid_io RO the number of non-page-size-aligned I/O requests +max_comp_streams RW the number of possible concurrent compress operations +comp_algorithm RW show and change the compression algorithm +notify_free RO the number of notifications to free pages (either + slot free notifications or REQ_DISCARD requests) +zero_pages RO the number of zero filled pages written to this disk +orig_data_size RO uncompressed size of data stored in this disk +compr_data_size RO compressed size of data stored in this disk +mem_used_total RO the amount of memory allocated for this disk +mem_used_max RW the maximum amount memory zram have consumed to + store compressed data +mem_limit RW the maximum amount of memory ZRAM can use to store + the compressed data +num_migrated RO the number of objects migrated migrated by compaction + + +WARNING +======= +per-stat sysfs attributes are considered to be deprecated. +The basic strategy is: +-- the existing RW nodes will be downgraded to WO nodes (in linux 4.11) +-- deprecated RO sysfs nodes will eventually be removed (in linux 4.11) + +The list of deprecated attributes can be found here: +Documentation/ABI/obsolete/sysfs-block-zram + +Basically, every attribute that has its own read accessible sysfs node +(e.g. num_reads) *AND* is accessible via one of the stat files (zram<id>/stat +or zram<id>/io_stat or zram<id>/mm_stat) is considered to be deprecated. + +User space is advised to use the following files to read the device statistics. + +File /sys/block/zram<id>/stat + +Represents block layer statistics. Read Documentation/block/stat.txt for +details. + +File /sys/block/zram<id>/io_stat + +The stat file represents device's I/O statistics not accounted by block +layer and, thus, not available in zram<id>/stat file. It consists of a +single line of text and contains the following stats separated by +whitespace: + failed_reads + failed_writes + invalid_io + notify_free + +File /sys/block/zram<id>/mm_stat + +The stat file represents device's mm statistics. It consists of a single +line of text and contains the following stats separated by whitespace: + orig_data_size + compr_data_size + mem_used_total + mem_limit + mem_used_max + zero_pages + num_migrated 8) Deactivate: swapoff /dev/zram0 |