Re: [PATCH] blk-throttle: ignore discard request size

On 08/18/2017 09:13 AM, Shaohua Li wrote:

discard request usually is very big and easily use all bandwidth budget
of a cgroup. discard request size doesn't really mean the size of data
written, so it doesn't make sense to account it into bandwidth budget.
This patch ignores discard requests size. It makes sense to account
discard request into iops budget though.

Some (most) devices to touch media for a discard operation, but the
cost tends to be fairly constant and independent of discard size.
Would it make sense to just treat it as a constant cost? Zero
cost seems wrong.

-- 
Jens Axboe