"Michael S. Tsirkin" <mst@xxxxxxxxxx> wrote on 05/05/2011 02:34:39 PM: > > It shows that 2.9% of the time, the 1 jiffy was not enough > > to free up space in the txq. > > How common is it to free up space in *less than* 1 jiffy? True, but the point is that the space freed is just enough for 43 entries, keeping it lower means a flood of (psuedo) stop's and restart's. > > That could also mean that we > > had set xmit_restart just before jiffies changed. But the > > average free capacity when we *resumed* xmits is: > > Sum of slots / (Good + Bad) = 43. > > > > So the delay of 1 jiffy helped the host clean up, on average, > > just 43 entries, which is 16% of total entries. This is > > intended to show that the guest is not sitting idle waiting > > for the jiffy to expire. > > OK, nice, this is exactly what my patchset is trying > to do, without playing with timers: tell the host > to interrupt us after 3/4 of the ring is free. > Why 3/4 and not all of the ring? My hope is we can > get some parallelism with the host this way. > Why 3/4 and not 7/8? No idea :) > > > > > > I can post it, mind testing this? > > > > > > > > Sure. > > > > > > Just posted. Would appreciate feedback. > > > > Do I need to apply all the patches and simply test? > > > > Thanks, > > > > - KK > > Exactly. You can also try to tune the threshold > for interrupts as well. Could you send me (privately) the entire virtio-net/vhost patch in a single file? It will help me quite a bit :) Either attachment or inline is fine. thanks, - KK -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
