zram: introduce per-device debug_stat sysfs node
debug_stat sysfs is read-only and represents various debugging data that
zram developers may need. This file is not meant to be used by anyone
else: its content is not documented and will change any time w/o any
notice. Therefore, the output of debug_stat file contains a version
string. To avoid any confusion, we will increase the version number
every time we modify the output.
At the moment this file exports only one value -- the number of
re-compressions, IOW, the number of times compression fast path has
failed. This stat is temporary any will be useful in case if any
per-cpu compression streams regressions will be reported.
Link: http://lkml.kernel.org/r/20160513230834.GB26763@bbox
Link: http://lkml.kernel.org/r/20160511134553.12655-1-sergey.senozhatsky@gmail.com
Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/Documentation/blockdev/zram.txt b/Documentation/blockdev/zram.txt
index d88f0c7..13100fb 100644
--- a/Documentation/blockdev/zram.txt
+++ b/Documentation/blockdev/zram.txt
@@ -172,6 +172,7 @@
pages_compacted RO the number of pages freed during compaction
(available only via zram<id>/mm_stat node)
compact WO trigger memory compaction
+debug_stat RO this file is used for zram debugging purposes
WARNING
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