On Tue, Mar 04, 2014 at 10:47:38AM +0100, Michal Privoznik wrote: > As I did previously in 4f588a1b46, libvirt needs to set virtio vectors. > Previously, we were advised to use vectors=N, where > > N = 2 * (number of queues) + 1 > > However, just recently this advisory has changed on the Multiquue wiki > page [1] to: > > N = 2 * (number of queues) + 2 > > 1: http://www.linux-kvm.org/page/Multiqueue#Enable_MQ_feature > > Signed-off-by: Michal Privoznik <mprivozn@xxxxxxxxxx> > --- > ACK > Notes: > I've had some discussion with qemu developers that qemu is the > best place to compute sane default [1]. And they agreed with me. > However, until they will do so, libvirt should pass the correct > value to make the whole feature work correctly. > > 1: https://bugzilla.redhat.com/show_bug.cgi?id=1005626 > I haven't read that, but making sure they'll make the change introspectable helps us decide whether we need to do that or not. Martin > src/qemu/qemu_command.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/src/qemu/qemu_command.c b/src/qemu/qemu_command.c > index ff0b2d5..18d0a64 100644 > --- a/src/qemu/qemu_command.c > +++ b/src/qemu/qemu_command.c > @@ -5036,8 +5036,8 @@ qemuBuildNicDevStr(virDomainDefPtr def, > } > if (usingVirtio && vhostfdSize > 1) { > /* As advised at http://www.linux-kvm.org/page/Multiqueue > - * we should add vectors=2*N+1 where N is the vhostfdSize */ > - virBufferAsprintf(&buf, ",mq=on,vectors=%d", 2 * vhostfdSize + 1); > + * we should add vectors=2*N+2 where N is the vhostfdSize */ > + virBufferAsprintf(&buf, ",mq=on,vectors=%d", 2 * vhostfdSize + 2); > } > if (vlan == -1) > virBufferAsprintf(&buf, ",netdev=host%s", net->info.alias); > -- > 1.9.0 > > -- > libvir-list mailing list > libvir-list@xxxxxxxxxx > https://www.redhat.com/mailman/listinfo/libvir-list
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