linux/Documentation/ABI/testing/sysfs-kernel-mm-cma

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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 09:37:28 +08:00
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/<cma-heap-name>/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/<cma-heap-name>/alloc_pages_fail
Date: Feb 2021
Contact: Minchan Kim <minchan@kernel.org>
Description:
the number of pages CMA API failed to allocate