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linux-imx/Documentation/ABI/testing/sysfs-kernel-mm-cma
Minchan Kim 43ca106fa8 mm: cma: support sysfs 
Since CMA is getting used more widely, it's more important to keep
monitoring CMA statistics for system health since it's directly related to
user experience.

This patch introduces sysfs statistics for CMA, in order to provide some
basic monitoring of the CMA allocator.

 * the number of CMA page successful allocations
 * the number of CMA page allocation failures

These two values allow the user to calcuate the allocation
failure rate for each CMA area.

e.g.)
  /sys/kernel/mm/cma/WIFI/alloc_pages_[success|fail]
  /sys/kernel/mm/cma/SENSOR/alloc_pages_[success|fail]
  /sys/kernel/mm/cma/BLUETOOTH/alloc_pages_[success|fail]

The cma_stat was intentionally allocated by dynamic allocation
to harmonize with kobject lifetime management.
https://lore.kernel.org/linux-mm/YCOAmXqt6dZkCQYs@kroah.com/

Link: https://lkml.kernel.org/r/20210324230759.2213957-1-minchan@kernel.org
Link: https://lore.kernel.org/linux-mm/20210316100433.17665-1-colin.king@canonical.com/
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Colin Ian King <colin.king@canonical.com>

Tested-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Dmitry Osipenko <digetx@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: John Hubbard <jhubbard@nvidia.com>
Tested-by: Anders Roxell <anders.roxell@linaro.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: John Dias <joaodias@google.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2021-05-05 11:27:24 -07:00

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What: /sys/kernel/mm/cma/ Date: Feb 2021 Contact: Minchan Kim minchan@kernel.org Description: /sys/kernel/mm/cma/ contains a subdirectory for each CMA heap name (also sometimes called CMA areas).

	Each CMA heap subdirectory (that is, each
	/sys/kernel/mm/cma/<cma-heap-name> directory) contains the
	following items:

		alloc_pages_success
		alloc_pages_fail

What: /sys/kernel/mm/cma//alloc_pages_success Date: Feb 2021 Contact: Minchan Kim minchan@kernel.org Description: the number of pages CMA API succeeded to allocate

What: /sys/kernel/mm/cma//alloc_pages_fail Date: Feb 2021 Contact: Minchan Kim minchan@kernel.org Description: the number of pages CMA API failed to allocate