Hi Stefan & Christoph, On 12/17/24 12:13 AM, Stefan Hajnoczi wrote: > On Mon, 16 Dec 2024 at 10:54, Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: >> >> Hacking passthrough into virtio_blk seems like not very good layering. >> If you have a use case where you want to use the core kernel virtio code >> but not the protocol drivers we'll probably need a virtqueue passthrough >> option of some kind. > > I think people are finding that submitting I/O via uring_cmd is faster > than traditional io_uring. The use case isn't really passthrough, it's > bypass :). Right, the initial purpose is bypassing the block layer (in the guest) to achieve better latency when the user process is operating on a raw virtio-blk device directly. > > 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. We are fine with that if it looks good to Jens. -- Thanks, Jingbo
