On Thu, Oct 28, 2010 at 12:32:35PM -0700, Shirley Ma wrote:

On Thu, 2010-10-28 at 07:20 +0200, Michael S. Tsirkin wrote:

quoted

My concern is this can delay signalling for unlimited time.
Could you pls test this with guests that do not have
2b5bbe3b8bee8b38bdc27dd9c0270829b6eb7eeb
b0c39dbdc204006ef3558a66716ff09797619778
that is 2.6.31 and older? 

The patch only induces delay signaling unlimited time when there is no
TX packet to transmit. I thought TX signaling only noticing guest to
release the used buffers, anything else beside this?

Right, that's it I think. For newer kernels we orphan the skb
on xmit so we don't care that much about completing them.
This does rely on an undocumented assumption about guest
behaviour though.

I tested rhel5u5 guest (2.6.18 kernel), it works fine. I checked the two
commits log, I don't think this patch could cause any issue w/o these
two patches.

Also I found a big TX regression for old guest and new guest. For old
guest, I am able to get almost 11Gb/s for 2K message size, but for the
new guest kernel, I can only get 3.5 Gb/s with the patch and same host.
I will dig it why.

thanks
Shirley