On Thu, May 05, 2011 at 03:13:43PM +0530, Krishna Kumar2 wrote: > "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, Sorry, which statement do you say is true? That interrupt after less than 1 jiffy is common? > 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 Better yet, here they are in git: git://git.kernel.org/pub/scm/linux/kernel/git/mst/vhost.git vhost-net-next-event-idx-v1 git://git.kernel.org/pub/scm/linux/kernel/git/mst/qemu-kvm.git virtio-net-event-idx-v1 -- MST -- 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
