On Wed, May 03, 2023 at 07:04:14AM +0200, Christoph Hellwig wrote: > On Mon, May 01, 2023 at 08:33:04AM -0700, Keith Busch wrote: > > From: Keith Busch <kbusch@xxxxxxxxxx> > > > > Passthrough requests don't go through the submit_bio() path, so all the > > overhead of setting up the bio's cgroup is wasted cycles. Provide a path > > to skip this setup. > > These days we should not need to set bi_bdev at all for passthrough, > so I think we can just drop the assingment. We can't really skip it for polling since that needs a bio with a bdev. I'll take another shot at detandling that requirement. > But instead of just optimizing for passthrough we really need to optimize > this assignment and get rid of the cost entirely. What is so expensive > about the cgroup lookup? Is this even for a device that uses cgroups > at all, or could we come up with a flag to bypass all the lookup unless > cgroup are anbled? It's not super expensive. It's just unnecessary for this usage and this seemed like the easiest way to avoid it.
