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authormst@redhat.com <mst@redhat.com>2011-02-01 22:13:42 +0200
committerAnthony Liguori <aliguori@us.ibm.com>2011-02-01 16:50:44 -0600
commit5430a28fe452907c9e1b2097e073bc1ea4b29f39 (patch)
tree066db9fdbac5a5ddca922b5d282161e9b6141b0e /net
parentf157ed202e51dc2492b201dc34ed28e89c973fb7 (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 'net')
-rw-r--r--net/tap.c6
1 files changed, 4 insertions, 2 deletions
diff --git a/net/tap.c b/net/tap.c
index eada34ac2..b8cd25267 100644
--- a/net/tap.c
+++ b/net/tap.c
@@ -491,8 +491,10 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan
}
}
- if (qemu_opt_get_bool(opts, "vhost", !!qemu_opt_get(opts, "vhostfd"))) {
+ if (qemu_opt_get_bool(opts, "vhost", !!qemu_opt_get(opts, "vhostfd") ||
+ qemu_opt_get_bool(opts, "vhostforce", false))) {
int vhostfd, r;
+ bool force = qemu_opt_get_bool(opts, "vhostforce", false);
if (qemu_opt_get(opts, "vhostfd")) {
r = net_handle_fd_param(mon, qemu_opt_get(opts, "vhostfd"));
if (r == -1) {
@@ -502,7 +504,7 @@ int net_init_tap(QemuOpts *opts, Monitor *mon, const char *name, VLANState *vlan
} else {
vhostfd = -1;
}
- s->vhost_net = vhost_net_init(&s->nc, vhostfd);
+ s->vhost_net = vhost_net_init(&s->nc, vhostfd, force);
if (!s->vhost_net) {
error_report("vhost-net requested but could not be initialized");
return -1;