Michael S. Tsirkin
2023-May-17 10:39 UTC
[PATCH v2 1/2] virtio: abstract virtqueue related methods
On Wed, May 17, 2023 at 04:35:55PM +0800, zhenwei pi wrote:> > > On 5/17/23 15:46, Christoph Hellwig wrote: > > On Wed, May 17, 2023 at 03:43:03PM +0800, zhenwei pi wrote: > > > I have a plan to introduce 'Virtio Over Fabrics'(TCP&RDMA) as Virtio > > > transport, as mentioned in cover letter of this series: > > > 3 weeks ago, I posted a proposal 'Virtio Over Fabrics': > > > https://lists.oasis-open.org/archives/virtio-comment/202304/msg00442.html > > > > Just don't do it. Please define your own protocols over RDMA or TCP > > for exactly the operations you need (for many they will already exist) > > instead of piggyg backing on virtio and making everyone else pay the > > price. > > > > Hi > > 1, `virtqueue_add_inbuf` in current version: > static inline int virtqueue_add_inbuf(struct virtqueue *vq, > struct scatterlist *sg, > unsigned int num, > void *data, > gfp_t gfp) > { > if (likely(!vq->abstract)) > return vring_virtqueue_add_sgs(vq, &sg, num, 0, 1, data, > NULL, gfp); > > return vq->add_sgs(vq, &sg, num, 0, 1, data, NULL, gfp); > } > > And disassemble 'virtinput_queue_evtbuf': > static void virtinput_queue_evtbuf(struct virtio_input *vi, > struct virtio_input_event *evtbuf) > { > struct scatterlist sg[1]; > > sg_init_one(sg, evtbuf, sizeof(*evtbuf)); > virtqueue_add_inbuf(vi->evt, sg, 1, evtbuf, GFP_ATOMIC); > } > > I notice that two instructions are newly added for vring like: > 24d: 80 78 35 00 cmpb $0x0,0x35(%rax) > 251: 75 3f jne 292 > > Is it an expensive price...Can we somehow only override the kick method? Then take the ring and send it over ...> 2, Storage/FS specific remote protocol is quite popular, otherwise I'm not > familiar with other device protocols. For example, I need a remote crypto > device to accelerate HTTPS ... With Virtio Over Fabrics, I have a chance to > attach a virtio-crypto device to do this work. > > -- > zhenwei pi
zhenwei pi
2023-May-18 00:47 UTC
[PATCH v2 1/2] virtio: abstract virtqueue related methods
On 5/17/23 18:39, Michael S. Tsirkin wrote:> On Wed, May 17, 2023 at 04:35:55PM +0800, zhenwei pi wrote: >> >> >> On 5/17/23 15:46, Christoph Hellwig wrote: >>> On Wed, May 17, 2023 at 03:43:03PM +0800, zhenwei pi wrote: >>>> I have a plan to introduce 'Virtio Over Fabrics'(TCP&RDMA) as Virtio >>>> transport, as mentioned in cover letter of this series: >>>> 3 weeks ago, I posted a proposal 'Virtio Over Fabrics': >>>> https://lists.oasis-open.org/archives/virtio-comment/202304/msg00442.html >>> >>> Just don't do it. Please define your own protocols over RDMA or TCP >>> for exactly the operations you need (for many they will already exist) >>> instead of piggyg backing on virtio and making everyone else pay the >>> price. >>> >> >> Hi >> >> 1, `virtqueue_add_inbuf` in current version: >> static inline int virtqueue_add_inbuf(struct virtqueue *vq, >> struct scatterlist *sg, >> unsigned int num, >> void *data, >> gfp_t gfp) >> { >> if (likely(!vq->abstract)) >> return vring_virtqueue_add_sgs(vq, &sg, num, 0, 1, data, >> NULL, gfp); >> >> return vq->add_sgs(vq, &sg, num, 0, 1, data, NULL, gfp); >> } >> >> And disassemble 'virtinput_queue_evtbuf': >> static void virtinput_queue_evtbuf(struct virtio_input *vi, >> struct virtio_input_event *evtbuf) >> { >> struct scatterlist sg[1]; >> >> sg_init_one(sg, evtbuf, sizeof(*evtbuf)); >> virtqueue_add_inbuf(vi->evt, sg, 1, evtbuf, GFP_ATOMIC); >> } >> >> I notice that two instructions are newly added for vring like: >> 24d: 80 78 35 00 cmpb $0x0,0x35(%rax) >> 251: 75 3f jne 292 >> >> Is it an expensive price... > > Can we somehow only override the kick method? > Then take the ring and send it over ... >Could you please take a look at this code? https://github.com/pizhenwei/linux/blob/virtio-of-github/drivers/virtio/virtio_fabrics.c#LL861C13-L861C23> >> 2, Storage/FS specific remote protocol is quite popular, otherwise I'm not >> familiar with other device protocols. For example, I need a remote crypto >> device to accelerate HTTPS ... With Virtio Over Fabrics, I have a chance to >> attach a virtio-crypto device to do this work. >> >> -- >> zhenwei pi >-- zhenwei pi