On 3/21/22 6:25 PM, Ming Lei wrote: > Hello, > > On Wed, Mar 16, 2022 at 09:27:08AM +0800, Ming Lei wrote: >> sbitmap has been used in scsi for replacing atomic operations on >> sdev->device_busy, so IOPS on some fast scsi storage can be improved. >> >> However, sdev->device_busy can be changed in fast path, so we have to >> allocate the sb->map statically. sdev->device_busy has been capped to 1024, >> but some drivers may configure the default depth as < 8, then >> cause each sbitmap word to hold only one bit. Finally 1024 * 128( >> sizeof(sbitmap_word)) bytes is needed for sb->map, given it is order 5 >> allocation, sometimes it may fail. >> >> Avoid the issue by using kvzalloc_node() for allocating sb->map. >> >> Cc: Ewan D. Milne <emilne@xxxxxxxxxx> >> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx> > > Ping... Was waiting on a response to the question on why we don't make this dependent on size, but upon look at kvzalloc_node(), this is already what it does. So I guess this looks fine to me too. -- Jens Axboe
