Since it's not stable until it could be merged into Linus's tree
lets make it as experimental. If a vendor want to use it, they
should carry on cma_sysfs.experimental=Y on kernel parameter.
Otherwise, it will be disabled.
If some vendor enables it, it means they know this is experimental
faeture so Android never guarantee it in the future.
Bug: 179256052
Signed-off-by: Minchan Kim <minchan@google.com>
Change-Id: Ic6566197a7865dfcab6964d008103d3686c9d14b
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://lore.kernel.org/linux-mm/20210324230759.2213957-1-minchan@kernel.org/
Bug: 179256052
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>
Link: https://lore.kernel.org/linux-mm/20210316100433.17665-1-colin.king@canonical.com/
Addresses-Coverity: ("Dereference after null check")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Minchan Kim <minchan@google.com>
Change-Id: I86239db91c7853a62a22b2161d1bf8c9099152b7
