commit f0c07c7c7b4fe4f9b63c88341fd32707def5a058
author Alex Williamson <alex.williamson@redhat.com> Thu Sep 02 09:00:50 2010 -0600
committer Michael S. Tsirkin <mst@redhat.com> Tue Sep 07 20:29:24 2010 +0300
tree 189a2c3e3a0a4877cf5e18c9e5968443eb3482c9
parent ca736c8e748e3bf77abe401231a412b9cdccb9d3

virtio-net: Make tx_timer timeout configurable

Add an option to make the TX mitigation timer adjustable as a device
option.  The 150us hard coded default used currently is reasonable,
but may not be suitable for all workloads, this gives us a way to
adjust it using a single binary.  We can't support any random option
though, so use the "x-" prefix to indicate this is a developer
option.  Usage:

-device virtio-net-pci,x-txtimer=500000,... # .5ms timeout

Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/virtio-net.c

diff --git a/hw/virtio-net.c b/hw/virtio-net.c
index 075f72d..d5b03ab 100644
--- a/hw/virtio-net.c
+++ b/hw/virtio-net.c
@@ -36,6 +36,7 @@
     VirtQueue *ctrl_vq;
     NICState *nic;
     QEMUTimer *tx_timer;
+    uint32_t tx_timeout;
     int tx_timer_active;
     uint32_t has_vnet_hdr;
     uint8_t has_ufo;
@@ -702,7 +703,7 @@
         virtio_net_flush_tx(n, vq);
     } else {
         qemu_mod_timer(n->tx_timer,
-                       qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
+                       qemu_get_clock(vm_clock) + n->tx_timeout);
         n->tx_timer_active = 1;
         virtio_queue_set_notification(vq, 0);
     }
@@ -842,7 +843,7 @@
 
     if (n->tx_timer_active) {
         qemu_mod_timer(n->tx_timer,
-                       qemu_get_clock(vm_clock) + TX_TIMER_INTERVAL);
+                       qemu_get_clock(vm_clock) + n->tx_timeout);
     }
     return 0;
 }
@@ -903,7 +904,8 @@
     virtio_net_set_status(&n->vdev, n->vdev.status & status);
 }
 
-VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf)
+VirtIODevice *virtio_net_init(DeviceState *dev, NICConf *conf,
+                              virtio_net_conf *net)
 {
     VirtIONet *n;
 
@@ -931,6 +933,7 @@
 
     n->tx_timer = qemu_new_timer(vm_clock, virtio_net_tx_timer, n);
     n->tx_timer_active = 0;
+    n->tx_timeout = net->txtimer;
     n->mergeable_rx_bufs = 0;
     n->promisc = 1; /* for compatibility */