android_kernel_xiaomi_sm8350/include
David Rientjes 2da02997e0 mm: add dirty_background_bytes and dirty_bytes sysctls
This change introduces two new sysctls to /proc/sys/vm:
dirty_background_bytes and dirty_bytes.

dirty_background_bytes is the counterpart to dirty_background_ratio and
dirty_bytes is the counterpart to dirty_ratio.

With growing memory capacities of individual machines, it's no longer
sufficient to specify dirty thresholds as a percentage of the amount of
dirtyable memory over the entire system.

dirty_background_bytes and dirty_bytes specify quantities of memory, in
bytes, that represent the dirty limits for the entire system.  If either
of these values is set, its value represents the amount of dirty memory
that is needed to commence either background or direct writeback.

When a `bytes' or `ratio' file is written, its counterpart becomes a
function of the written value.  For example, if dirty_bytes is written to
be 8096, 8K of memory is required to commence direct writeback.
dirty_ratio is then functionally equivalent to 8K / the amount of
dirtyable memory:

	dirtyable_memory = free pages + mapped pages + file cache

	dirty_background_bytes = dirty_background_ratio * dirtyable_memory
		-or-
	dirty_background_ratio = dirty_background_bytes / dirtyable_memory

		AND

	dirty_bytes = dirty_ratio * dirtyable_memory
		-or-
	dirty_ratio = dirty_bytes / dirtyable_memory

Only one of dirty_background_bytes and dirty_background_ratio may be
specified at a time, and only one of dirty_bytes and dirty_ratio may be
specified.  When one sysctl is written, the other appears as 0 when read.

The `bytes' files operate on a page size granularity since dirty limits
are compared with ZVC values, which are in page units.

Prior to this change, the minimum dirty_ratio was 5 as implemented by
get_dirty_limits() although /proc/sys/vm/dirty_ratio would show any user
written value between 0 and 100.  This restriction is maintained, but
dirty_bytes has a lower limit of only one page.

Also prior to this change, the dirty_background_ratio could not equal or
exceed dirty_ratio.  This restriction is maintained in addition to
restricting dirty_background_bytes.  If either background threshold equals
or exceeds that of the dirty threshold, it is implicitly set to half the
dirty threshold.

Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Andrea Righi <righi.andrea@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-01-06 15:59:03 -08:00
..
acpi cpumask: convert shared_cpu_map in acpi_processor* structs to cpumask_var_t 2009-01-03 19:15:40 +01:00
asm-arm
asm-frv frv: define __fls 2009-01-03 16:14:05 +10:30
asm-generic Merge branch 'cpus4096-for-linus-2' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip 2009-01-02 11:44:09 -08:00
asm-h8300
asm-m32r m32r: define __fls 2009-01-03 16:16:54 +10:30
asm-m68k m68k: define __fls 2009-01-01 10:12:18 +10:30
asm-mn10300 mn10300: define __fls 2009-01-03 16:19:03 +10:30
asm-xtensa xtensa: define __fls 2009-01-03 16:21:08 +10:30
crypto crypto: aes - Precompute tables 2008-12-25 11:05:13 +11:00
drm drm: Add a debug node for vblank state. 2008-12-29 17:47:27 +10:00
keys
linux mm: add dirty_background_bytes and dirty_bytes sysctls 2009-01-06 15:59:03 -08:00
math-emu
media V4L/DVB (10141): v4l2: debugging API changed to match against driver name instead of ID. 2009-01-02 17:11:52 -02:00
mtd
net ipv6: Fix sporadic sendmsg -EINVAL when sending to multicast groups. 2009-01-04 16:04:39 -08:00
pcmcia
rdma
rxrpc
scsi [SCSI] fcoe: Fibre Channel over Ethernet 2008-12-29 11:24:33 -06:00
sound V4L/DVB (10135): v4l2: introduce v4l2_file_operations. 2009-01-02 17:11:12 -02:00
trace sched, trace: update trace_sched_wakeup() 2008-12-25 13:10:21 +01:00
video video: sh_mobile_lcdcfb deferred io support 2008-12-22 18:44:48 +09:00
xen
Kbuild