Re: [PATCH] Increase the tx queue to 512 descriptors to fix performance problem.

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Dor Laor wrote:
On Wed, 2008-01-09 at 08:29 -0600, Anthony Liguori wrote:
Dor Laor wrote:
Now that we have a host timer based tx wakeup it waits for 64
packets or timeout before processing them.
This might cause the guest to run out of tx buffers while the host
holds them up.
There's a proper fix that Rusty added last night.

This is with his latest patch, without it I got a lot of
"printk("Unlikely: restart svq failed\n");"
+ The performance is much better now.

How are you getting that? What are you running and what is your guest kernel? I've not seen that before.


This is a temporal solution to quickly bring back performance to 800mbps.
But a better fix will soon be sent (its not the only problem).
How are you doing performance testing?

Not really, this was just to stabilize the module.
It needs some more work, disable/enable of the device is broken.

What do you mean by disable/enable? FWIW, your patch really hurts netperf performance which is why I asked how you were measuring 800mbps.

Regards,

Anthony Liguori


Regards,

Anthony Liguori

Signed-off-by: Dor Laor <dor.laor@xxxxxxxxxxxx>
---
 qemu/hw/virtio-net.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/qemu/hw/virtio-net.c b/qemu/hw/virtio-net.c
index 777fe2c..3d07b65 100644
--- a/qemu/hw/virtio-net.c
+++ b/qemu/hw/virtio-net.c
@@ -293,7 +293,7 @@ void *virtio_net_init(PCIBus *bus, NICInfo *nd, int devfn)
     n->vdev.update_config = virtio_net_update_config;
     n->vdev.get_features = virtio_net_get_features;
     n->rx_vq = virtio_add_queue(&n->vdev, 512, virtio_net_handle_rx);
-    n->tx_vq = virtio_add_queue(&n->vdev, 128, virtio_net_handle_tx);
+    n->tx_vq = virtio_add_queue(&n->vdev, 512, virtio_net_handle_tx);
     n->can_receive = 0;
     memcpy(n->mac, nd->macaddr, 6);
     n->vc = qemu_new_vlan_client(nd->vlan, virtio_net_receive,

_______________________________________________
Virtualization mailing list
Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
https://lists.linux-foundation.org/mailman/listinfo/virtualization

[Index of Archives]     [KVM Development]     [Libvirt Development]     [Libvirt Users]     [CentOS Virtualization]     [Netdev]     [Ethernet Bridging]     [Linux Wireless]     [Kernel Newbies]     [Security]     [Linux for Hams]     [Netfilter]     [Bugtraq]     [Yosemite Forum]     [MIPS Linux]     [ARM Linux]     [Linux RAID]     [Linux Admin]     [Samba]

  Powered by Linux