On Thu, Sep 29, 2022 at 12:59:46PM +0300, Sagi Grimberg wrote: > > 3. Do you have some performance numbers (we're touching the fast path > > here) ? > > This is pretty light-weight, accounting is per-cpu and only wrapped by > preemption disable. This is a very small price to pay for what we gain. It does add up, though, and some environments disable stats to skip the overhead. At a minimum, you need to add a check for blk_queue_io_stat() before assuming you need to account for stats. Instead of duplicating the accounting, could you just have the stats file report the sum of its hidden devices?
