Re: [PATCH 10/17] block: wire-up support for plugging

Ming Lei
2022-03-14T14:41:16Z

On Thu, Mar 10, 2022 at 06:10:08PM +0530, Kanchan Joshi wrote:
> On Thu, Mar 10, 2022 at 2:04 PM Christoph Hellwig <hch@lst.de> wrote:
> >
> > On Tue, Mar 08, 2022 at 08:50:58PM +0530, Kanchan Joshi wrote:
> > > From: Jens Axboe <axboe@kernel.dk>
> > >
> > > Add support to use plugging if it is enabled, else use default path.
> >
> > The subject and this comment don't really explain what is done, and
> > also don't mention at all why it is done.
>
> Missed out, will fix up. But plugging gave a very good hike to IOPS.

But how does plugging improve IOPS here for passthrough request? Not
see plug->nr_ios is wired to data.nr_tags in blk_mq_alloc_request(),
which is called by nvme_submit_user_cmd().

Thanks,
Ming