On Tue, Sep 27, 2022 at 7:14 AM Jens Axboe <axboe@xxxxxxxxx> wrote: > > Hi, > > The passthrough IO path currently doesn't do any request allocation > batching like we do for normal IO. Wire this up through the usual > blk_mq_alloc_request() allocation helper. > > Similarly, we don't currently supported batched completions for > passthrough IO. Allow the request->end_io() handler to return back > whether or not it retains ownership of the request. By default all > handlers are converted to returning RQ_END_IO_NONE, which retains > the existing behavior. But with that in place, we can tweak the > nvme uring_cmd end_io handler to pass back ownership, and hence enable > completion batching for passthrough requests as well. > > This is good for a 10% improvement for passthrough performance. For > a non-drive limited test case, passthrough IO is now more efficient > than the regular bdev O_DIRECT path. > > Changes since v1: > - Remove spurious semicolon > - Cleanup struct nvme_uring_cmd_pdu handling > > -- > Jens Axboe > > I see an improvement of ~12% (2.34 to 2.63 MIOPS) with polling enabled and an improvement of ~4% (1.84 to 1.92 MIOPS) with polling disabled using the t/io_uring utility (in fio) in my setup with this patch series! -- Anuj Gupta
