From: "Michael S. Tsirkin" <mst@redhat.com> To: Paolo Bonzini <pbonzini@redhat.com> Cc: linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org, kvm@vger.kernel.org, rusty@rustcorp.com.au, jasowang@redhat.com, virtualization@lists.linux-foundation.org Subject: Re: [PATCH 5/5] virtio-scsi: introduce multiqueue support Date: Tue, 4 Sep 2012 18:03:23 +0300 [thread overview] Message-ID: <20120904150323.GA15116@redhat.com> (raw) In-Reply-To: <5046167C.3070109@redhat.com> On Tue, Sep 04, 2012 at 04:55:56PM +0200, Paolo Bonzini wrote: > Il 04/09/2012 16:47, Michael S. Tsirkin ha scritto: > >> > static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, > >> > - struct virtqueue *vq) > >> > + struct virtqueue *vq, bool affinity) > >> > { > >> > spin_lock_init(&virtscsi_vq->vq_lock); > >> > virtscsi_vq->vq = vq; > >> > + if (affinity) > >> > + virtqueue_set_affinity(vq, virtqueue_get_queue_index(vq) - > >> > + VIRTIO_SCSI_VQ_BASE); > >> > } > >> > > > This means in practice if you have less virtqueues than CPUs, > > things are not going to work well, will they? > > Not particularly. It could be better or worse than single queue > depending on the workload. Well interrupts will go to CPU different from the one that sends commands so ... > > Any idea what to do? > > Two possibilities: > > 1) Add a stride argument to virtqueue_set_affinity, and make it equal to > the number of queues. > > 2) Make multiqueue the default in QEMU, and make the default number of > queues equal to the number of VCPUs. > > I was going for (2). > > Paolo 3. use per target queue if less targets than cpus? -- MST
WARNING: multiple messages have this Message-ID (diff)
From: "Michael S. Tsirkin" <mst@redhat.com> To: Paolo Bonzini <pbonzini@redhat.com> Cc: kvm@vger.kernel.org, linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org Subject: Re: [PATCH 5/5] virtio-scsi: introduce multiqueue support Date: Tue, 4 Sep 2012 18:03:23 +0300 [thread overview] Message-ID: <20120904150323.GA15116@redhat.com> (raw) In-Reply-To: <5046167C.3070109@redhat.com> On Tue, Sep 04, 2012 at 04:55:56PM +0200, Paolo Bonzini wrote: > Il 04/09/2012 16:47, Michael S. Tsirkin ha scritto: > >> > static void virtscsi_init_vq(struct virtio_scsi_vq *virtscsi_vq, > >> > - struct virtqueue *vq) > >> > + struct virtqueue *vq, bool affinity) > >> > { > >> > spin_lock_init(&virtscsi_vq->vq_lock); > >> > virtscsi_vq->vq = vq; > >> > + if (affinity) > >> > + virtqueue_set_affinity(vq, virtqueue_get_queue_index(vq) - > >> > + VIRTIO_SCSI_VQ_BASE); > >> > } > >> > > > This means in practice if you have less virtqueues than CPUs, > > things are not going to work well, will they? > > Not particularly. It could be better or worse than single queue > depending on the workload. Well interrupts will go to CPU different from the one that sends commands so ... > > Any idea what to do? > > Two possibilities: > > 1) Add a stride argument to virtqueue_set_affinity, and make it equal to > the number of queues. > > 2) Make multiqueue the default in QEMU, and make the default number of > queues equal to the number of VCPUs. > > I was going for (2). > > Paolo 3. use per target queue if less targets than cpus? -- MST
next prev parent reply other threads:[~2012-09-04 15:02 UTC|newest] Thread overview: 68+ messages / expand[flat|nested] mbox.gz Atom feed top 2012-08-28 11:54 [PATCH 0/5] Multiqueue virtio-scsi Paolo Bonzini 2012-08-28 11:54 ` Paolo Bonzini 2012-08-28 11:54 ` [PATCH 1/5] virtio-ring: move queue_index to vring_virtqueue Paolo Bonzini 2012-08-28 11:54 ` Paolo Bonzini 2012-08-29 7:54 ` Jason Wang 2012-08-29 7:54 ` Jason Wang 2012-09-05 23:32 ` Rusty Russell 2012-09-05 23:32 ` Rusty Russell 2012-08-28 11:54 ` [PATCH 2/5] virtio: introduce an API to set affinity for a virtqueue Paolo Bonzini 2012-08-28 11:54 ` Paolo Bonzini 2012-09-05 23:32 ` Rusty Russell 2012-09-05 23:32 ` Rusty Russell 2012-08-28 11:54 ` [PATCH 3/5] virtio-scsi: allocate target pointers in a separate memory block Paolo Bonzini 2012-08-28 11:54 ` Paolo Bonzini 2012-08-28 14:07 ` Sasha Levin 2012-08-28 14:07 ` Sasha Levin 2012-08-28 14:25 ` Paolo Bonzini 2012-08-28 14:25 ` Paolo Bonzini 2012-08-28 11:54 ` [PATCH 4/5] virtio-scsi: pass struct virtio_scsi to virtqueue completion function Paolo Bonzini 2012-08-28 11:54 ` Paolo Bonzini 2012-08-28 11:54 ` [PATCH 5/5] virtio-scsi: introduce multiqueue support Paolo Bonzini 2012-08-28 11:54 ` Paolo Bonzini 2012-09-04 2:21 ` Nicholas A. Bellinger 2012-09-04 2:21 ` Nicholas A. Bellinger 2012-09-04 6:46 ` Paolo Bonzini 2012-09-04 6:46 ` Paolo Bonzini 2012-09-04 8:46 ` Michael S. Tsirkin 2012-09-04 8:46 ` Michael S. Tsirkin 2012-09-04 10:25 ` Paolo Bonzini 2012-09-04 10:25 ` Paolo Bonzini 2012-09-04 11:09 ` Michael S. Tsirkin 2012-09-04 11:09 ` Michael S. Tsirkin 2012-09-04 11:18 ` Paolo Bonzini 2012-09-04 11:18 ` Paolo Bonzini 2012-09-04 13:35 ` Michael S. Tsirkin 2012-09-04 13:35 ` Michael S. Tsirkin 2012-09-04 13:45 ` Paolo Bonzini 2012-09-04 13:45 ` Paolo Bonzini 2012-09-04 14:19 ` Michael S. Tsirkin 2012-09-04 14:19 ` Michael S. Tsirkin 2012-09-04 14:25 ` Paolo Bonzini 2012-09-04 14:25 ` Paolo Bonzini 2012-09-04 20:11 ` Nicholas A. Bellinger 2012-09-04 20:11 ` Nicholas A. Bellinger 2012-09-05 7:03 ` Paolo Bonzini 2012-09-05 7:03 ` Paolo Bonzini 2012-09-04 12:48 ` Michael S. Tsirkin 2012-09-04 12:48 ` Michael S. Tsirkin 2012-09-04 13:49 ` Paolo Bonzini 2012-09-04 13:49 ` Paolo Bonzini 2012-09-04 14:21 ` Michael S. Tsirkin 2012-09-04 14:21 ` Michael S. Tsirkin 2012-09-04 14:30 ` Paolo Bonzini 2012-09-04 14:30 ` Paolo Bonzini 2012-09-04 14:41 ` Michael S. Tsirkin 2012-09-04 14:41 ` Michael S. Tsirkin 2012-09-04 14:47 ` Michael S. Tsirkin 2012-09-04 14:47 ` Michael S. Tsirkin 2012-09-04 14:55 ` Paolo Bonzini 2012-09-04 14:55 ` Paolo Bonzini 2012-09-04 15:03 ` Michael S. Tsirkin [this message] 2012-09-04 15:03 ` Michael S. Tsirkin 2012-08-30 7:13 ` [PATCH 0/5] Multiqueue virtio-scsi Stefan Hajnoczi 2012-08-30 7:13 ` Stefan Hajnoczi 2012-08-30 14:53 ` Michael S. Tsirkin 2012-08-30 14:53 ` Michael S. Tsirkin 2012-08-30 15:45 ` Paolo Bonzini 2012-08-30 15:45 ` Paolo Bonzini
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20120904150323.GA15116@redhat.com \ --to=mst@redhat.com \ --cc=jasowang@redhat.com \ --cc=kvm@vger.kernel.org \ --cc=linux-kernel@vger.kernel.org \ --cc=linux-scsi@vger.kernel.org \ --cc=pbonzini@redhat.com \ --cc=rusty@rustcorp.com.au \ --cc=virtualization@lists.linux-foundation.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: linkBe sure your reply has a Subject: header at the top and a blank line before the message body.
This is an external index of several public inboxes, see mirroring instructions on how to clone and mirror all data and code used by this external index.