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Re: [Qemu-devel] [PATCH V7 15/16] virtio-pci: increase the maximum numbe


From: Jason Wang
Subject: Re: [Qemu-devel] [PATCH V7 15/16] virtio-pci: increase the maximum number of virtqueues to 513
Date: Tue, 28 Apr 2015 11:05:18 +0800



On Thu, Apr 23, 2015 at 7:24 PM, Cornelia Huck <address@hidden> wrote:
On Thu, 23 Apr 2015 14:21:48 +0800
Jason Wang <address@hidden> wrote:

This patch increases the maximum number of virtqueues for pci from 64 to 513. This will allow booting a virtio-net-pci device with 256 queue
     ^^^

pairs on recent Linux host (which supports up to 256 tuntap queue pairs). To keep migration compatibility, 64 was kept for legacy machine types. This is because qemu in fact allows guest to probe the limit of
 virtqueues through trying to set queue_sel. So for legacy machine
 type, we should make sure setting queue_sel to more than 63 won't
 make effect.
Cc: Paolo Bonzini <address@hidden>
 Cc: Richard Henderson <address@hidden>
 Cc: Michael S. Tsirkin <address@hidden>
 Cc: Alexander Graf <address@hidden>
 Cc: address@hidden
 Signed-off-by: Jason Wang <address@hidden>
 ---
  hw/i386/pc_piix.c      | 5 +++++
  hw/i386/pc_q35.c       | 5 +++++
  hw/ppc/spapr.c         | 5 +++++
  hw/virtio/virtio-pci.c | 6 +++++-
  4 files changed, 20 insertions(+), 1 deletion(-)
(...)
 diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
 index 7d01500..c510cb7 100644
 --- a/hw/virtio/virtio-pci.c
 +++ b/hw/virtio/virtio-pci.c
 @@ -42,7 +42,11 @@
   * configuration space */
#define VIRTIO_PCI_CONFIG_SIZE(dev) VIRTIO_PCI_CONFIG_OFF(msix_enabled(dev)) -#define VIRTIO_PCI_QUEUE_MAX 64 +/* The number was chose to be greater than both the the number of max + * vcpus supported by host and the number of max tuntap queues support
 + * by host and also leave some spaces for future.
 + */
 +#define VIRTIO_PCI_QUEUE_MAX 1024
                                ^^^^

I think you need to fixup subject and patch description :)

Yes, will fix this.

Thanks

static void virtio_pci_bus_new(VirtioBusState *bus, size_t bus_size,
                                 VirtIOPCIProxy *dev);





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