Re: [PATCH] lib/sbitmap: allocate sb->map via kvzalloc_node

[Chaitanya Kulkarni <chaitanyak@nvidia.com>]

On 3/15/22 18:27, 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@redhat.com>
> Signed-off-by: Ming Lei <ming.lei@redhat.com>
> ---
>

maybe considering the total size before actual allocation
that will not buy us anything ?

Looks good.

Reviewed-by: Chaitanya Kulkarni <kch@nvidia.com>

-ck