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On 18/11/2015 06:47, Ming Lin wrote: > @@ -726,7 +798,11 @@ static void nvme_process_db(NvmeCtrl *n, hwaddr addr, int val) > } > > start_sqs = nvme_cq_full(cq) ? 1 : 0; > - cq->head = new_head; > + /* When the mapped pointer memory area is setup, we don't rely on > + * the MMIO written values to update the head pointer. */ > + if (!cq->db_addr) { > + cq->head = new_head; > + } You are still checking if (new_head &...

On 18/11/2015 06:47, Ming Lin wrote: > @@ -726,7 +798,11 @@ static void nvme_process_db(NvmeCtrl *n, hwaddr addr, int val) > } > > start_sqs = nvme_cq_full(cq) ? 1 : 0; > - cq->head = new_head; > + /* When the mapped pointer memory area is setup, we don't rely on > + * the MMIO written values to update the head pointer. */ > + if (!cq->db_addr) { > + cq->head = new_head; > + } You are still checking if (new_head &...

...nzini wrote: >> >> On 18/11/2015 06:47, Ming Lin wrote: >>> @@ -726,7 +798,11 @@ static void nvme_process_db(NvmeCtrl *n, hwaddr addr, int val) >>> } >>> >>> start_sqs = nvme_cq_full(cq) ? 1 : 0; >>> - cq->head = new_head; >>> + /* When the mapped pointer memory area is setup, we don't rely on >>> + * the MMIO written values to update the head pointer. */ >>> + if (!cq->db_addr) { >>> + cq->head = new_head; >>> + } >&gt...

...nzini wrote: >> >> On 18/11/2015 06:47, Ming Lin wrote: >>> @@ -726,7 +798,11 @@ static void nvme_process_db(NvmeCtrl *n, hwaddr addr, int val) >>> } >>> >>> start_sqs = nvme_cq_full(cq) ? 1 : 0; >>> - cq->head = new_head; >>> + /* When the mapped pointer memory area is setup, we don't rely on >>> + * the MMIO written values to update the head pointer. */ >>> + if (!cq->db_addr) { >>> + cq->head = new_head; >>> + } >&gt...

...11:37 +0100, Paolo Bonzini wrote: > > On 18/11/2015 06:47, Ming Lin wrote: > > @@ -726,7 +798,11 @@ static void nvme_process_db(NvmeCtrl *n, hwaddr addr, int val) > > } > > > > start_sqs = nvme_cq_full(cq) ? 1 : 0; > > - cq->head = new_head; > > + /* When the mapped pointer memory area is setup, we don't rely on > > + * the MMIO written values to update the head pointer. */ > > + if (!cq->db_addr) { > > + cq->head = new_head; > > + } > > You are sti...

...-ro > > Then it doesn't response input for almost 1 minute. > Without this patch, kernel loads quickly. Interesting. I guess there's time to debug it, since QEMU 2.6 is still a few months away. In the meanwhile we can apply your patch as is, apart from disabling the "if (new_head >= cq->size)" and the similar one for "if (new_ tail >= sq->size". But, I have a possible culprit. In your nvme_cq_notifier you are not doing the equivalent of: start_sqs = nvme_cq_full(cq) ? 1 : 0; cq->head = new_head; if (start_sqs) {...

...;> On 18/11/2015 06:47, Ming Lin wrote: > >>> @@ -726,7 +798,11 @@ static void nvme_process_db(NvmeCtrl *n, hwaddr addr, int val) > >>> } > >>> > >>> start_sqs = nvme_cq_full(cq) ? 1 : 0; > >>> - cq->head = new_head; > >>> + /* When the mapped pointer memory area is setup, we don't rely on > >>> + * the MMIO written values to update the head pointer. */ > >>> + if (!cq->db_addr) { > >>> + cq->head = new_head; > >&g...

Hi Rob & Mihai, I wrote vhost-nvme patches on top of Christoph's NVMe target. vhost-nvme still uses mmio. So the guest OS can run unmodified NVMe driver. But the tests I have done didn't show competitive performance compared to virtio-blk/virtio-scsi. The bottleneck is in mmio. Your nvme vendor extension patches reduces greatly the number of MMIO writes. So I'd like to push it

Hi Rob & Mihai, I wrote vhost-nvme patches on top of Christoph's NVMe target. vhost-nvme still uses mmio. So the guest OS can run unmodified NVMe driver. But the tests I have done didn't show competitive performance compared to virtio-blk/virtio-scsi. The bottleneck is in mmio. Your nvme vendor extension patches reduces greatly the number of MMIO writes. So I'd like to push it

...me_enqueue_req_completion(cq, req); } + + nvme_update_sq_eventidx(sq); + nvme_update_sq_tail(sq); } } @@ -726,7 +798,11 @@ static void nvme_process_db(NvmeCtrl *n, hwaddr addr, int val) } start_sqs = nvme_cq_full(cq) ? 1 : 0; - cq->head = new_head; + /* When the mapped pointer memory area is setup, we don't rely on + * the MMIO written values to update the head pointer. */ + if (!cq->db_addr) { + cq->head = new_head; + } if (start_sqs) { NvmeSQueue *sq; QTAI...

Hi, This is the first attempt to add a new qemu nvme backend using in-kernel nvme target. Most code are ported from qemu-nvme and also borrow code from Hannes Reinecke's rts-megasas. It's similar as vhost-scsi, but doesn't use virtio. The advantage is guest can run unmodified NVMe driver. So guest can be any OS that has a NVMe driver. The goal is to get as good performance as

Hi, This is the first attempt to add a new qemu nvme backend using in-kernel nvme target. Most code are ported from qemu-nvme and also borrow code from Hannes Reinecke's rts-megasas. It's similar as vhost-scsi, but doesn't use virtio. The advantage is guest can run unmodified NVMe driver. So guest can be any OS that has a NVMe driver. The goal is to get as good performance as