linux-kernel - Re: [PATCH 0/3][RFC] virtio-blk: add io_uring passthrough support for virtio-blk

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Message-ID: <acaf46f3-3f6c-44c9-86b5-98aa7845f1b6@kernel.dk>
Date: Tue, 17 Dec 2024 10:54:26 -0700
From: Jens Axboe <axboe@...nel.dk>
To: Jingbo Xu <jefflexu@...ux.alibaba.com>,
 Stefan Hajnoczi <stefanha@...il.com>, Christoph Hellwig <hch@...radead.org>
Cc: Ferry Meng <mengferry@...ux.alibaba.com>,
 "Michael S . Tsirkin" <mst@...hat.com>, Jason Wang <jasowang@...hat.com>,
 linux-block@...r.kernel.org, virtualization@...ts.linux.dev,
 linux-kernel@...r.kernel.org, io-uring@...r.kernel.org,
 Joseph Qi <joseph.qi@...ux.alibaba.com>
Subject: Re: [PATCH 0/3][RFC] virtio-blk: add io_uring passthrough support for
 virtio-blk

On 12/16/24 11:08 PM, Jingbo Xu wrote:
>> That's why I asked Jens to weigh in on whether there is a generic
>> block layer solution here. If uring_cmd is faster then maybe a generic
>> uring_cmd I/O interface can be defined without tying applications to
>> device-specific commands. Or maybe the traditional io_uring code path
>> can be optimized so that bypass is no longer attractive.

It's not that the traditional io_uring code path is slower, it's in fact
basically the same thing. It's that all the other jazz that happens
below io_uring slows things down, which is why passthrough ends up being
faster.

-- 
Jens Axboe