frontend not being notified about packets received?

frontend not being notified about packets received?

[James Harper]

I'm working on the windows xen pv drivers in Andy's absence, and am
noticing a strange behaviour... I'm not getting a notification of
packets received until there are lots of them, then I get them all at
once, but up to a minute or so later if there isn't much activity.

I have tinkered with setting "feature-rx-notify" to zero and one, and
omitting it altogether, but it doesn't appear to change anything.

Any hints would be greatly appreciated. I'm using the latest Debian
2.6.18 packages from Etch, and Xen 3.1.1.

Thanks

James

Re: frontend not being notified about packets received?

[Ralph Passgang]

Am Samstag, 29. Dezember 2007 12:56:13 schrieb James Harper:
> I'm working on the windows xen pv drivers in Andy's absence, and am
> noticing a strange behaviour... I'm not getting a notification of
> packets received until there are lots of them, then I get them all at
> once, but up to a minute or so later if there isn't much activity.
>
> I have tinkered with setting "feature-rx-notify" to zero and one, and
> omitting it altogether, but it doesn't appear to change anything.
>
> Any hints would be greatly appreciated. I'm using the latest Debian
> 2.6.18 packages from Etch, and Xen 3.1.1.

Just a hint: The debian 2.6.18-5-xen packages are made with patches from xen 
3.0 and not with a more recent 3.1 patch.

I am not familiar enough with the xen internals to say if this could be the 
problem, but maybe you should compile 2.6.18 with a more recent xen patch 
to see if the problem still exists then.

btw.: I tried your xen pv drivers (v0.5) on win xp 32bit. They are working 
very well. They are not really faster, but at least they reduce the load in 
dom0 a lot on heavy IO in the hvm guest. So after optimising them for 
speed, they really could be usefull for all win hvm setups.

Some things I noticed: you need a hvm domain with apic/acpi enabled (haven't 
checked which one is really required), because without apic/acpi the pv 
drivers will generate a blue screen at boot time.

So keep the good work up! I really like to see open source pv drivers for 
windows! Let me know if it helps you to see some benchmarks on the harddisk 
performance.

--Ralph

> Thanks
>
> James
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel

RE: frontend not being notified about packets received?

[James Harper]

> 
> I'm working on the windows xen pv drivers in Andy's absence, and am
> noticing a strange behaviour... I'm not getting a notification of
> packets received until there are lots of them, then I get them all at
> once, but up to a minute or so later if there isn't much activity.
> 
> I have tinkered with setting "feature-rx-notify" to zero and one, and
> omitting it altogether, but it doesn't appear to change anything.
> 
> Any hints would be greatly appreciated. I'm using the latest Debian
> 2.6.18 packages from Etch, and Xen 3.1.1.
> 

Found the problem. rsp_event wasn't being set properly.

For anyone who's interested, xennet now appears to basically be working.
I am able to get a DHCP address from a Linux server, and ping it,
although arp seems to take longer than it should to sort itself out, and
it seems to muck up your existing qemu network adapter too (forgets it's
static IP address etc).

Ping latency drops from around 400us with the qemu drivers to about
200us with the PV drivers. I haven't tested much else at this stage.

The above updates are all in hg.

James

Re: frontend not being notified about packets received?

[Mark Williamson]

> Found the problem. rsp_event wasn't being set properly.

I was just wondering if it was that!  Glad you sorted it anyhow.

> For anyone who's interested, xennet now appears to basically be working.
> I am able to get a DHCP address from a Linux server, and ping it,
> although arp seems to take longer than it should to sort itself out, and
> it seems to muck up your existing qemu network adapter too (forgets it's
> static IP address etc).
>
> Ping latency drops from around 400us with the qemu drivers to about
> 200us with the PV drivers. I haven't tested much else at this stage.

Wooo! :-)  Lookin' good!

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!