diff options
| author | mst@redhat.com <mst@redhat.com> | 2011-02-01 22:13:42 +0200 |
|---|---|---|
| committer | Anthony Liguori <aliguori@us.ibm.com> | 2011-02-01 16:50:44 -0600 |
| commit | 5430a28fe452907c9e1b2097e073bc1ea4b29f39 (patch) | |
| tree | 066db9fdbac5a5ddca922b5d282161e9b6141b0e /qemu-options.hx | |
| parent | f157ed202e51dc2492b201dc34ed28e89c973fb7 (diff) | |
vhost: force vhost off for non-MSI guests
When MSI is off, each interrupt needs to be bounced through the io
thread when it's set/cleared, so vhost-net causes more context switches and
higher CPU utilization than userspace virtio which handles networking in
the same thread.
We'll need to fix this by adding level irq support in kvm irqfd,
for now disable vhost-net in these configurations.
Added a vhostforce flag to force vhost-net back on.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'qemu-options.hx')
| -rw-r--r-- | qemu-options.hx | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/qemu-options.hx b/qemu-options.hx index 598a1bdf77..945edf3562 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -1050,7 +1050,7 @@ DEF("net", HAS_ARG, QEMU_OPTION_net, "-net tap[,vlan=n][,name=str],ifname=name\n" " connect the host TAP network interface to VLAN 'n'\n" #else - "-net tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off][,vhostfd=h]\n" + "-net tap[,vlan=n][,name=str][,fd=h][,ifname=name][,script=file][,downscript=dfile][,sndbuf=nbytes][,vnet_hdr=on|off][,vhost=on|off][,vhostfd=h][,vhostforce=on|off]\n" " connect the host TAP network interface to VLAN 'n' and use the\n" " network scripts 'file' (default=" DEFAULT_NETWORK_SCRIPT ")\n" " and 'dfile' (default=" DEFAULT_NETWORK_DOWN_SCRIPT ")\n" @@ -1061,6 +1061,8 @@ DEF("net", HAS_ARG, QEMU_OPTION_net, " use vnet_hdr=off to avoid enabling the IFF_VNET_HDR tap flag\n" " use vnet_hdr=on to make the lack of IFF_VNET_HDR support an error condition\n" " use vhost=on to enable experimental in kernel accelerator\n" + " (only has effect for virtio guests which use MSIX)\n" + " use vhostforce=on to force vhost on for non-MSIX virtio guests\n" " use 'vhostfd=h' to connect to an already opened vhost net device\n" #endif "-net socket[,vlan=n][,name=str][,fd=h][,listen=[host]:port][,connect=host:port]\n" |