From: Cornelia Huck <cohuck@redhat.com>
To: Stefan Hajnoczi <stefanha@redhat.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Fam Zheng <fam@euphon.net>,
Eduardo Habkost <ehabkost@redhat.com>,
qemu-block@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>,
qemu-devel@nongnu.org, Max Reitz <mreitz@redhat.com>,
Paolo Bonzini <pbonzini@redhat.com>
Subject: Re: [PATCH v2 2/4] virtio-scsi: default num_queues to -smp N
Date: Mon, 27 Jan 2020 14:10:31 +0100 [thread overview]
Message-ID: <20200127141031.6e108839.cohuck@redhat.com> (raw)
In-Reply-To: <20200124100159.736209-3-stefanha@redhat.com>
On Fri, 24 Jan 2020 10:01:57 +0000
Stefan Hajnoczi <stefanha@redhat.com> wrote:
> Automatically size the number of request virtqueues to match the number
"If the pci transport is used, ..." ?
> of vCPUs. This ensures that completion interrupts are handled on the
> same vCPU that submitted the request. No IPI is necessary to complete
> an I/O request and performance is improved.
"For other transports, the number of request queues continues to
default to 1." ?
>
> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
> ---
> hw/core/machine.c | 3 +++
> hw/scsi/vhost-scsi.c | 3 ++-
> hw/scsi/vhost-user-scsi.c | 3 ++-
> hw/scsi/virtio-scsi.c | 6 +++++-
> hw/virtio/vhost-scsi-pci.c | 10 ++++++++--
> hw/virtio/vhost-user-scsi-pci.c | 10 ++++++++--
> hw/virtio/virtio-scsi-pci.c | 10 ++++++++--
> include/hw/virtio/virtio-scsi.h | 2 ++
> 8 files changed, 38 insertions(+), 9 deletions(-)
>
(...)
> diff --git a/hw/virtio/vhost-scsi-pci.c b/hw/virtio/vhost-scsi-pci.c
> index e8dfbfc60f..38a8f0c3ef 100644
> --- a/hw/virtio/vhost-scsi-pci.c
> +++ b/hw/virtio/vhost-scsi-pci.c
> @@ -17,6 +17,7 @@
> #include "qemu/osdep.h"
>
> #include "standard-headers/linux/virtio_pci.h"
> +#include "hw/boards.h"
> #include "hw/qdev-properties.h"
> #include "hw/virtio/vhost-scsi.h"
> #include "qapi/error.h"
> @@ -47,10 +48,15 @@ static void vhost_scsi_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp)
> {
> VHostSCSIPCI *dev = VHOST_SCSI_PCI(vpci_dev);
> DeviceState *vdev = DEVICE(&dev->vdev);
> - VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev);
> + VirtIOSCSIConf *conf = &dev->vdev.parent_obj.parent_obj.conf;
> +
> + /* 1:1 vq to vcpu mapping is ideal because it avoids IPIs */
> + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) {
> + conf->num_queues = current_machine->smp.cpus;
This now maps the request vqs 1:1 to the vcpus. What about the fixed
vqs? If they don't really matter, amend the comment to explain that?
> + }
>
> if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) {
> - vpci_dev->nvectors = vs->conf.num_queues + 3;
> + vpci_dev->nvectors = conf->num_queues + VIRTIO_SCSI_VQ_NUM_FIXED + 1;
> }
>
> qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus));
next prev parent reply other threads:[~2020-01-27 13:11 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-24 10:01 [PATCH v2 0/4] virtio-pci: enable blk and scsi multi-queue by default Stefan Hajnoczi
2020-01-24 10:01 ` [PATCH v2 1/4] virtio-scsi: introduce a constant for fixed virtqueues Stefan Hajnoczi
2020-01-27 12:59 ` Cornelia Huck
2020-01-24 10:01 ` [PATCH v2 2/4] virtio-scsi: default num_queues to -smp N Stefan Hajnoczi
2020-01-27 13:10 ` Cornelia Huck [this message]
2020-01-29 15:44 ` Stefan Hajnoczi
2020-01-30 0:29 ` Paolo Bonzini
2020-01-30 10:52 ` Stefan Hajnoczi
2020-01-30 11:03 ` Cornelia Huck
2020-02-03 10:25 ` Sergio Lopez
2020-02-03 10:35 ` Michael S. Tsirkin
2020-02-03 10:51 ` Cornelia Huck
2020-02-03 10:57 ` Daniel P. Berrangé
2020-02-03 11:39 ` Sergio Lopez
2020-02-03 12:53 ` Michael S. Tsirkin
2020-02-11 16:20 ` Stefan Hajnoczi
2020-02-11 16:31 ` Michael S. Tsirkin
2020-02-12 11:18 ` Stefan Hajnoczi
2020-02-21 10:55 ` Stefan Hajnoczi
2020-01-24 10:01 ` [PATCH v2 3/4] virtio-blk: " Stefan Hajnoczi
2020-01-27 13:14 ` Cornelia Huck
2020-01-24 10:01 ` [PATCH v2 4/4] vhost-user-blk: " Stefan Hajnoczi
2020-01-27 13:17 ` Cornelia Huck
2020-01-27 9:59 ` [PATCH v2 0/4] virtio-pci: enable blk and scsi multi-queue by default Stefano Garzarella
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