| Message ID | 20200527102925.128013-4-stefanha@redhat.com |
|---|---|
| State | New |
| Headers | show |
| Series | virtio-pci: enable blk and scsi multi-queue by default | expand |
On Wed, May 27, 2020 at 11:29:23AM +0100, Stefan Hajnoczi wrote: > Automatically size the number of virtio-scsi-pci, vhost-scsi-pci, and > vhost-user-scsi-pci request virtqueues to match the number of vCPUs. > Other transports continue to default to 1 request virtqueue. IIRC this was raised on earlier versions of the series, but i don't recall the outcome and no caveats are mentioned here... Is this default still valid for very large $vCPUs. eg if I run QEMU with "-smp 512" or even larger (I've seen people discussing 1000's of CPUs), is this going to cause problems with the virtio-scsi default queue counts ? Is there such a thing as "too large" for the num of queues setting ? num vectors defaults to a value derived from num queues, so is there concept of "too large" for num of vectors setting ? Ideally the commit message would answer these questions for future reference. Same for the next patch to virtio-blk > > A 1:1 virtqueue:vCPU mapping 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. > > Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> > --- > include/hw/virtio/virtio-scsi.h | 2 ++ > hw/core/machine.c | 6 +++++- > 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 +++++++--- > 8 files changed, 37 insertions(+), 13 deletions(-) > > diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h > index 9f293bcb80..c0b8e4dd7e 100644 > --- a/include/hw/virtio/virtio-scsi.h > +++ b/include/hw/virtio/virtio-scsi.h > @@ -39,6 +39,8 @@ > /* Number of virtqueues that are always present */ > #define VIRTIO_SCSI_VQ_NUM_FIXED 2 > > +#define VIRTIO_SCSI_AUTO_NUM_QUEUES UINT32_MAX > + > typedef struct virtio_scsi_cmd_req VirtIOSCSICmdReq; > typedef struct virtio_scsi_cmd_resp VirtIOSCSICmdResp; > typedef struct virtio_scsi_ctrl_tmf_req VirtIOSCSICtrlTMFReq; > diff --git a/hw/core/machine.c b/hw/core/machine.c > index bb3a7b18b1..df7664bc8d 100644 > --- a/hw/core/machine.c > +++ b/hw/core/machine.c > @@ -28,7 +28,11 @@ > #include "hw/mem/nvdimm.h" > #include "migration/vmstate.h" > > -GlobalProperty hw_compat_5_0[] = {}; > +GlobalProperty hw_compat_5_0[] = { > + { "virtio-scsi-device", "num_queues", "1"}, > + { "vhost-scsi", "num_queues", "1"}, > + { "vhost-user-scsi", "num_queues", "1"}, > +}; > const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0); > > GlobalProperty hw_compat_4_2[] = { > diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c > index c1b012aea4..5e3bc319ab 100644 > --- a/hw/scsi/vhost-scsi.c > +++ b/hw/scsi/vhost-scsi.c > @@ -272,7 +272,8 @@ static Property vhost_scsi_properties[] = { > DEFINE_PROP_STRING("vhostfd", VirtIOSCSICommon, conf.vhostfd), > DEFINE_PROP_STRING("wwpn", VirtIOSCSICommon, conf.wwpn), > DEFINE_PROP_UINT32("boot_tpgt", VirtIOSCSICommon, conf.boot_tpgt, 0), > - DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues, 1), > + DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues, > + VIRTIO_SCSI_AUTO_NUM_QUEUES), > DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSICommon, conf.virtqueue_size, > 128), > DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSICommon, conf.seg_max_adjust, > diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c > index f8bd158c31..4b56de97a8 100644 > --- a/hw/scsi/vhost-user-scsi.c > +++ b/hw/scsi/vhost-user-scsi.c > @@ -163,7 +163,8 @@ static void vhost_user_scsi_unrealize(DeviceState *dev) > static Property vhost_user_scsi_properties[] = { > DEFINE_PROP_CHR("chardev", VirtIOSCSICommon, conf.chardev), > DEFINE_PROP_UINT32("boot_tpgt", VirtIOSCSICommon, conf.boot_tpgt, 0), > - DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues, 1), > + DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues, > + VIRTIO_SCSI_AUTO_NUM_QUEUES), > DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSICommon, conf.virtqueue_size, > 128), > DEFINE_PROP_UINT32("max_sectors", VirtIOSCSICommon, conf.max_sectors, > diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c > index f3d60683bd..f055ae7389 100644 > --- a/hw/scsi/virtio-scsi.c > +++ b/hw/scsi/virtio-scsi.c > @@ -891,6 +891,9 @@ void virtio_scsi_common_realize(DeviceState *dev, > virtio_init(vdev, "virtio-scsi", VIRTIO_ID_SCSI, > sizeof(VirtIOSCSIConfig)); > > + if (s->conf.num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { > + s->conf.num_queues = 1; > + } > if (s->conf.num_queues == 0 || > s->conf.num_queues > VIRTIO_QUEUE_MAX - VIRTIO_SCSI_VQ_NUM_FIXED) { > error_setg(errp, "Invalid number of queues (= %" PRIu32 "), " > @@ -964,7 +967,8 @@ static void virtio_scsi_device_unrealize(DeviceState *dev) > } > > static Property virtio_scsi_properties[] = { > - DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues, 1), > + DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues, > + VIRTIO_SCSI_AUTO_NUM_QUEUES), > DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSI, > parent_obj.conf.virtqueue_size, 256), > DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSI, > diff --git a/hw/virtio/vhost-scsi-pci.c b/hw/virtio/vhost-scsi-pci.c > index 2b25db9a3c..9f377a84cf 100644 > --- a/hw/virtio/vhost-scsi-pci.c > +++ b/hw/virtio/vhost-scsi-pci.c > @@ -47,11 +47,15 @@ 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; > + > + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { > + conf->num_queues = > + virtio_pci_optimal_num_queues(VIRTIO_SCSI_VQ_NUM_FIXED); > + } > > if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) { > - vpci_dev->nvectors = vs->conf.num_queues + > - VIRTIO_SCSI_VQ_NUM_FIXED + 1; > + vpci_dev->nvectors = conf->num_queues + VIRTIO_SCSI_VQ_NUM_FIXED + 1; > } > > qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus)); > diff --git a/hw/virtio/vhost-user-scsi-pci.c b/hw/virtio/vhost-user-scsi-pci.c > index 80710ab170..2a4c0d27f1 100644 > --- a/hw/virtio/vhost-user-scsi-pci.c > +++ b/hw/virtio/vhost-user-scsi-pci.c > @@ -53,11 +53,15 @@ static void vhost_user_scsi_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) > { > VHostUserSCSIPCI *dev = VHOST_USER_SCSI_PCI(vpci_dev); > DeviceState *vdev = DEVICE(&dev->vdev); > - VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev); > + VirtIOSCSIConf *conf = &dev->vdev.parent_obj.parent_obj.conf; > + > + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { > + conf->num_queues = > + virtio_pci_optimal_num_queues(VIRTIO_SCSI_VQ_NUM_FIXED); > + } > > if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) { > - vpci_dev->nvectors = vs->conf.num_queues + > - VIRTIO_SCSI_VQ_NUM_FIXED + 1; > + vpci_dev->nvectors = conf->num_queues + VIRTIO_SCSI_VQ_NUM_FIXED + 1; > } > > qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus)); > diff --git a/hw/virtio/virtio-scsi-pci.c b/hw/virtio/virtio-scsi-pci.c > index c52d68053a..c3e2f8625a 100644 > --- a/hw/virtio/virtio-scsi-pci.c > +++ b/hw/virtio/virtio-scsi-pci.c > @@ -46,13 +46,17 @@ static void virtio_scsi_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) > { > VirtIOSCSIPCI *dev = VIRTIO_SCSI_PCI(vpci_dev); > DeviceState *vdev = DEVICE(&dev->vdev); > - VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev); > DeviceState *proxy = DEVICE(vpci_dev); > + VirtIOSCSIConf *conf = &dev->vdev.parent_obj.conf; > char *bus_name; > > + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { > + conf->num_queues = > + virtio_pci_optimal_num_queues(VIRTIO_SCSI_VQ_NUM_FIXED); > + } > + > if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) { > - vpci_dev->nvectors = vs->conf.num_queues + > - VIRTIO_SCSI_VQ_NUM_FIXED + 1; > + vpci_dev->nvectors = conf->num_queues + VIRTIO_SCSI_VQ_NUM_FIXED + 1; > } > > /* > -- > 2.25.4 > Regards, Daniel
On Wed, May 27, 2020 at 11:38:17AM +0100, Daniel P. Berrangé wrote: > On Wed, May 27, 2020 at 11:29:23AM +0100, Stefan Hajnoczi wrote: > > Automatically size the number of virtio-scsi-pci, vhost-scsi-pci, and > > vhost-user-scsi-pci request virtqueues to match the number of vCPUs. > > Other transports continue to default to 1 request virtqueue. > > IIRC this was raised on earlier versions of the series, but i don't > recall the outcome and no caveats are mentioned here... > > Is this default still valid for very large $vCPUs. eg if I run QEMU > with "-smp 512" or even larger (I've seen people discussing 1000's of > CPUs), is this going to cause problems with the virtio-scsi default > queue counts ? Is there such a thing as "too large" for the num > of queues setting ? num vectors defaults to a value derived from > num queues, so is there concept of "too large" for num of vectors > setting ? > > Ideally the commit message would answer these questions for future > reference. Same for the next patch to virtio-blk Good point. Actually this patch and the virtio-blk ones no longer contain the queue number policy. The new virtio_pci_optimal_num_queues() function encapsulates the policy to avoid duplication. I'll resend and update that patch with the full rationale. Thanks!
diff --git a/include/hw/virtio/virtio-scsi.h b/include/hw/virtio/virtio-scsi.h index 9f293bcb80..c0b8e4dd7e 100644 --- a/include/hw/virtio/virtio-scsi.h +++ b/include/hw/virtio/virtio-scsi.h @@ -39,6 +39,8 @@ /* Number of virtqueues that are always present */ #define VIRTIO_SCSI_VQ_NUM_FIXED 2 +#define VIRTIO_SCSI_AUTO_NUM_QUEUES UINT32_MAX + typedef struct virtio_scsi_cmd_req VirtIOSCSICmdReq; typedef struct virtio_scsi_cmd_resp VirtIOSCSICmdResp; typedef struct virtio_scsi_ctrl_tmf_req VirtIOSCSICtrlTMFReq; diff --git a/hw/core/machine.c b/hw/core/machine.c index bb3a7b18b1..df7664bc8d 100644 --- a/hw/core/machine.c +++ b/hw/core/machine.c @@ -28,7 +28,11 @@ #include "hw/mem/nvdimm.h" #include "migration/vmstate.h" -GlobalProperty hw_compat_5_0[] = {}; +GlobalProperty hw_compat_5_0[] = { + { "virtio-scsi-device", "num_queues", "1"}, + { "vhost-scsi", "num_queues", "1"}, + { "vhost-user-scsi", "num_queues", "1"}, +}; const size_t hw_compat_5_0_len = G_N_ELEMENTS(hw_compat_5_0); GlobalProperty hw_compat_4_2[] = { diff --git a/hw/scsi/vhost-scsi.c b/hw/scsi/vhost-scsi.c index c1b012aea4..5e3bc319ab 100644 --- a/hw/scsi/vhost-scsi.c +++ b/hw/scsi/vhost-scsi.c @@ -272,7 +272,8 @@ static Property vhost_scsi_properties[] = { DEFINE_PROP_STRING("vhostfd", VirtIOSCSICommon, conf.vhostfd), DEFINE_PROP_STRING("wwpn", VirtIOSCSICommon, conf.wwpn), DEFINE_PROP_UINT32("boot_tpgt", VirtIOSCSICommon, conf.boot_tpgt, 0), - DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues, 1), + DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues, + VIRTIO_SCSI_AUTO_NUM_QUEUES), DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSICommon, conf.virtqueue_size, 128), DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSICommon, conf.seg_max_adjust, diff --git a/hw/scsi/vhost-user-scsi.c b/hw/scsi/vhost-user-scsi.c index f8bd158c31..4b56de97a8 100644 --- a/hw/scsi/vhost-user-scsi.c +++ b/hw/scsi/vhost-user-scsi.c @@ -163,7 +163,8 @@ static void vhost_user_scsi_unrealize(DeviceState *dev) static Property vhost_user_scsi_properties[] = { DEFINE_PROP_CHR("chardev", VirtIOSCSICommon, conf.chardev), DEFINE_PROP_UINT32("boot_tpgt", VirtIOSCSICommon, conf.boot_tpgt, 0), - DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues, 1), + DEFINE_PROP_UINT32("num_queues", VirtIOSCSICommon, conf.num_queues, + VIRTIO_SCSI_AUTO_NUM_QUEUES), DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSICommon, conf.virtqueue_size, 128), DEFINE_PROP_UINT32("max_sectors", VirtIOSCSICommon, conf.max_sectors, diff --git a/hw/scsi/virtio-scsi.c b/hw/scsi/virtio-scsi.c index f3d60683bd..f055ae7389 100644 --- a/hw/scsi/virtio-scsi.c +++ b/hw/scsi/virtio-scsi.c @@ -891,6 +891,9 @@ void virtio_scsi_common_realize(DeviceState *dev, virtio_init(vdev, "virtio-scsi", VIRTIO_ID_SCSI, sizeof(VirtIOSCSIConfig)); + if (s->conf.num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { + s->conf.num_queues = 1; + } if (s->conf.num_queues == 0 || s->conf.num_queues > VIRTIO_QUEUE_MAX - VIRTIO_SCSI_VQ_NUM_FIXED) { error_setg(errp, "Invalid number of queues (= %" PRIu32 "), " @@ -964,7 +967,8 @@ static void virtio_scsi_device_unrealize(DeviceState *dev) } static Property virtio_scsi_properties[] = { - DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues, 1), + DEFINE_PROP_UINT32("num_queues", VirtIOSCSI, parent_obj.conf.num_queues, + VIRTIO_SCSI_AUTO_NUM_QUEUES), DEFINE_PROP_UINT32("virtqueue_size", VirtIOSCSI, parent_obj.conf.virtqueue_size, 256), DEFINE_PROP_BOOL("seg_max_adjust", VirtIOSCSI, diff --git a/hw/virtio/vhost-scsi-pci.c b/hw/virtio/vhost-scsi-pci.c index 2b25db9a3c..9f377a84cf 100644 --- a/hw/virtio/vhost-scsi-pci.c +++ b/hw/virtio/vhost-scsi-pci.c @@ -47,11 +47,15 @@ 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; + + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { + conf->num_queues = + virtio_pci_optimal_num_queues(VIRTIO_SCSI_VQ_NUM_FIXED); + } if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) { - vpci_dev->nvectors = vs->conf.num_queues + - VIRTIO_SCSI_VQ_NUM_FIXED + 1; + vpci_dev->nvectors = conf->num_queues + VIRTIO_SCSI_VQ_NUM_FIXED + 1; } qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus)); diff --git a/hw/virtio/vhost-user-scsi-pci.c b/hw/virtio/vhost-user-scsi-pci.c index 80710ab170..2a4c0d27f1 100644 --- a/hw/virtio/vhost-user-scsi-pci.c +++ b/hw/virtio/vhost-user-scsi-pci.c @@ -53,11 +53,15 @@ static void vhost_user_scsi_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) { VHostUserSCSIPCI *dev = VHOST_USER_SCSI_PCI(vpci_dev); DeviceState *vdev = DEVICE(&dev->vdev); - VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev); + VirtIOSCSIConf *conf = &dev->vdev.parent_obj.parent_obj.conf; + + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { + conf->num_queues = + virtio_pci_optimal_num_queues(VIRTIO_SCSI_VQ_NUM_FIXED); + } if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) { - vpci_dev->nvectors = vs->conf.num_queues + - VIRTIO_SCSI_VQ_NUM_FIXED + 1; + vpci_dev->nvectors = conf->num_queues + VIRTIO_SCSI_VQ_NUM_FIXED + 1; } qdev_set_parent_bus(vdev, BUS(&vpci_dev->bus)); diff --git a/hw/virtio/virtio-scsi-pci.c b/hw/virtio/virtio-scsi-pci.c index c52d68053a..c3e2f8625a 100644 --- a/hw/virtio/virtio-scsi-pci.c +++ b/hw/virtio/virtio-scsi-pci.c @@ -46,13 +46,17 @@ static void virtio_scsi_pci_realize(VirtIOPCIProxy *vpci_dev, Error **errp) { VirtIOSCSIPCI *dev = VIRTIO_SCSI_PCI(vpci_dev); DeviceState *vdev = DEVICE(&dev->vdev); - VirtIOSCSICommon *vs = VIRTIO_SCSI_COMMON(vdev); DeviceState *proxy = DEVICE(vpci_dev); + VirtIOSCSIConf *conf = &dev->vdev.parent_obj.conf; char *bus_name; + if (conf->num_queues == VIRTIO_SCSI_AUTO_NUM_QUEUES) { + conf->num_queues = + virtio_pci_optimal_num_queues(VIRTIO_SCSI_VQ_NUM_FIXED); + } + if (vpci_dev->nvectors == DEV_NVECTORS_UNSPECIFIED) { - vpci_dev->nvectors = vs->conf.num_queues + - VIRTIO_SCSI_VQ_NUM_FIXED + 1; + vpci_dev->nvectors = conf->num_queues + VIRTIO_SCSI_VQ_NUM_FIXED + 1; } /*
Automatically size the number of virtio-scsi-pci, vhost-scsi-pci, and vhost-user-scsi-pci request virtqueues to match the number of vCPUs. Other transports continue to default to 1 request virtqueue. A 1:1 virtqueue:vCPU mapping 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. Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> --- include/hw/virtio/virtio-scsi.h | 2 ++ hw/core/machine.c | 6 +++++- 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 +++++++--- 8 files changed, 37 insertions(+), 13 deletions(-)