Commit 77db7bb5 authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Andrew Morton
Browse files

zram: add incompressible flag to read_block_state() 

Add a new flag to zram block state that shows if the page is
incompressible: that none of the algorithm (including secondary ones)
could compress it.

Link: https://lkml.kernel.org/r/20221109115047.2921851-14-senozhatsky@chromium.org


Suggested-by: default avatarMinchan Kim <minchan@kernel.org>
Signed-off-by: default avatarSergey Senozhatsky <senozhatsky@chromium.org>
Acked-by: default avatarMinchan Kim <minchan@kernel.org>
Cc: Alexey Romanov <avromanov@sberdevices.ru>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: Nitin Gupta <ngupta@vflare.org>
Cc: Suleiman Souhlal <suleiman@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent b46f9ea3

Documentation/admin-guide/blockdev/zram.rst

+7 −4
Original line number Diff line number Diff line
@@ -497,10 +497,11 @@ pages of the process with*pagemap. 
If you enable the feature, you could see block state via

/sys/kernel/debug/zram/zram0/block_state". The output is as follows::



	  300    75.033841 .wh..

	  301    63.806904 s....

	  302    63.806919 ..hi.

	  303    62.801919 ....r

	  300    75.033841 .wh...

	  301    63.806904 s.....

	  302    63.806919 ..hi..

	  303    62.801919 ....r.

	  304   146.781902 ..hi.n



First column

	zram's block index.
@@ -519,6 +520,8 @@ Third column 
		idle page

	r:

		recompressed page (secondary compression algorithm)

	n:

		none (including secondary) of algorithms could compress it



First line of above example says 300th block is accessed at 75.033841sec

and the block's state is huge so it is written back to the backing

drivers/block/zram/zram_drv.c

+4 −2
Original line number Diff line number Diff line
@@ -946,14 +946,16 @@ static ssize_t read_block_state(struct file *file, char __user *buf, 


		ts = ktime_to_timespec64(zram->table[index].ac_time);

		copied = snprintf(kbuf + written, count,

			"%12zd %12lld.%06lu %c%c%c%c%c\n",

			"%12zd %12lld.%06lu %c%c%c%c%c%c\n",

			index, (s64)ts.tv_sec,

			ts.tv_nsec / NSEC_PER_USEC,

			zram_test_flag(zram, index, ZRAM_SAME) ? 's' : '.',

			zram_test_flag(zram, index, ZRAM_WB) ? 'w' : '.',

			zram_test_flag(zram, index, ZRAM_HUGE) ? 'h' : '.',

			zram_test_flag(zram, index, ZRAM_IDLE) ? 'i' : '.',

			zram_get_priority(zram, index) ? 'r' : '.');

			zram_get_priority(zram, index) ? 'r' : '.',

			zram_test_flag(zram, index,

				       ZRAM_INCOMPRESSIBLE) ? 'n' : '.');



		if (count <= copied) {

			zram_slot_unlock(zram, index);