Merge android-4.9.155 (32e6695) into msm-4.9 (2f8eb1ca) · Commits · e / devices / android_kernel_fairphone_FP3

Documentation/ABI/testing/sysfs-block-zram

+39 −0

Original line number	Diff line number	Diff line
		@@ -98,3 +98,42 @@ Description:
		The backing_dev file is read-write and set up backing
		device for zram to write incompressible pages.
		For using, user should enable CONFIG_ZRAM_WRITEBACK.

		What: /sys/block/zram<id>/idle
		Date: November 2018
		Contact: Minchan Kim <minchan@kernel.org>
		Description:
		idle file is write-only and mark zram slot as idle.
		If system has mounted debugfs, user can see which slots
		are idle via /sys/kernel/debug/zram/zram<id>/block_state

		What: /sys/block/zram<id>/writeback
		Date: November 2018
		Contact: Minchan Kim <minchan@kernel.org>
		Description:
		The writeback file is write-only and trigger idle and/or
		huge page writeback to backing device.

		What: /sys/block/zram<id>/bd_stat
		Date: November 2018
		Contact: Minchan Kim <minchan@kernel.org>
		Description:
		The bd_stat file is read-only and represents backing device's
		statistics (bd_count, bd_reads, bd_writes) in a format
		similar to block layer statistics file format.

		What: /sys/block/zram<id>/writeback_limit_enable
		Date: November 2018
		Contact: Minchan Kim <minchan@kernel.org>
		Description:
		The writeback_limit_enable file is read-write and specifies
		eanbe of writeback_limit feature. "1" means eable the feature.
		No limit "0" is the initial state.

		What: /sys/block/zram<id>/writeback_limit
		Date: November 2018
		Contact: Minchan Kim <minchan@kernel.org>
		Description:
		The writeback_limit file is read-write and specifies the maximum
		amount of writeback ZRAM can do. The limit could be changed
		in run time.

Documentation/blockdev/zram.txt

+105 −21

Original line number	Diff line number	Diff line
		@@ -164,11 +164,15 @@ reset WO trigger device reset
		mem_used_max WO reset the `mem_used_max' counter (see later)
		mem_limit WO specifies the maximum amount of memory ZRAM can use
		to store the compressed data
		writeback_limit WO specifies the maximum amount of write IO zram can
		write out to backing device as 4KB unit
		writeback_limit_enable RW show and set writeback_limit feature
		max_comp_streams RW the number of possible concurrent compress operations
		comp_algorithm RW show and change the compression algorithm
		compact WO trigger memory compaction
		debug_stat RO this file is used for zram debugging purposes
		backing_dev RW set up backend storage for zram to write out
		idle WO mark allocated slot as idle


		User space is advised to use the following files to read the device statistics.
		@@ -220,6 +224,17 @@ line of text and contains the following stats separated by whitespace:
		pages_compacted the number of pages freed during compaction
		huge_pages the number of incompressible pages

		File /sys/block/zram<id>/bd_stat

		The stat file represents device's backing device statistics. It consists of
		a single line of text and contains the following stats separated by whitespace:
		bd_count size of data written in backing device.
		Unit: 4K bytes
		bd_reads the number of reads from backing device
		Unit: 4K bytes
		bd_writes the number of writes to backing device
		Unit: 4K bytes

		9) Deactivate:
		swapoff /dev/zram0
		umount /dev/zram1
		@@ -237,11 +252,79 @@ line of text and contains the following stats separated by whitespace:

		= writeback

		With incompressible pages, there is no memory saving with zram.
		Instead, with CONFIG_ZRAM_WRITEBACK, zram can write incompressible page
		With CONFIG_ZRAM_WRITEBACK, zram can write idle/incompressible page
		to backing storage rather than keeping it in memory.
		User should set up backing device via /sys/block/zramX/backing_dev
		before disksize setting.
		To use the feature, admin should set up backing device via

		"echo /dev/sda5 > /sys/block/zramX/backing_dev"

		before disksize setting. It supports only partition at this moment.
		If admin want to use incompressible page writeback, they could do via

		"echo huge > /sys/block/zramX/write"

		To use idle page writeback, first, user need to declare zram pages
		as idle.

		"echo all > /sys/block/zramX/idle"

		From now on, any pages on zram are idle pages. The idle mark
		will be removed until someone request access of the block.
		IOW, unless there is access request, those pages are still idle pages.

		Admin can request writeback of those idle pages at right timing via

		"echo idle > /sys/block/zramX/writeback"

		With the command, zram writeback idle pages from memory to the storage.

		If there are lots of write IO with flash device, potentially, it has
		flash wearout problem so that admin needs to design write limitation
		to guarantee storage health for entire product life.

		To overcome the concern, zram supports "writeback_limit" feature.
		The "writeback_limit_enable"'s default value is 0 so that it doesn't limit
		any writeback. IOW, if admin want to apply writeback budget, he should
		enable writeback_limit_enable via

		$ echo 1 > /sys/block/zramX/writeback_limit_enable

		Once writeback_limit_enable is set, zram doesn't allow any writeback
		until admin set the budget via /sys/block/zramX/writeback_limit.

		(If admin doesn't enable writeback_limit_enable, writeback_limit's value
		assigned via /sys/block/zramX/writeback_limit is meaninless.)

		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.
		$ echo 1 > /sys/block/zram0/writeback_limit_enable

		If admin want to allow further write again once the bugdet is exausted,
		he could do it like below

		$ echo $((400<<MB_SHIFT>>4K_SHIFT)) > \
		/sys/block/zram0/writeback_limit

		If admin want to see remaining writeback budget since he set,

		$ cat /sys/block/zramX/writeback_limit

		If admin want to disable writeback limit, he could do

		$ echo 0 > /sys/block/zramX/writeback_limit_enable

		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.

		If admin want to measure writeback count in a certain period, he could
		know it via /sys/block/zram0/bd_stat's 3rd column.

		= memory tracking

		@@ -251,16 +334,17 @@ 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 ..h
		300 75.033841 .wh.
		301 63.806904 s...
		302 63.806919 ..hi

		First column is zram's block index.
		Second column is access time since the system was booted
		Third column is state of the block.
		(s: same page
		w: written page to backing store
		h: huge page)
		h: huge page
		i: idle page)

		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

Documentation/filesystems/proc.txt

+3 −1

Original line number	Diff line number	Diff line
		@@ -488,7 +488,9 @@ manner. The codes are the following:

		Note that there is no guarantee that every flag and associated mnemonic will
		be present in all further kernel releases. Things get changed, the flags may
		be vanished or the reverse -- new added.
		be vanished or the reverse -- new added. Interpretation of their meaning
		might change in future as well. So each consumer of these flags has to
		follow each specific kernel version for the exact semantic.

		The "Name" field will only be present on a mapping that has been named by
		userspace, and will show the name passed in by userspace.

Makefile

+1 −1

Original line number	Diff line number	Diff line
		VERSION = 4
		PATCHLEVEL = 9
		SUBLEVEL = 152
		SUBLEVEL = 155
		EXTRAVERSION =
		NAME = Roaring Lionus

arch/arc/include/asm/perf_event.h

+2 −1

Original line number	Diff line number	Diff line
		@@ -103,7 +103,8 @@ static const char * const arc_pmu_ev_hw_map[] = {

		/* counts condition */
		[PERF_COUNT_HW_INSTRUCTIONS] = "iall",
		[PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = "ijmp", /* Excludes ZOL jumps */
		/* All jump instructions that are taken */
		[PERF_COUNT_HW_BRANCH_INSTRUCTIONS] = "ijmptak",
		[PERF_COUNT_ARC_BPOK] = "bpok", /* NP-NT, PT-T, PNT-NT */
		#ifdef CONFIG_ISA_ARCV2
		[PERF_COUNT_HW_BRANCH_MISSES] = "bpmp",