Re: [Xen-devel] More network tests with xenoprofile this time

[Andrew Theurer <habanero@xxxxxxxxxx>]

On Tuesday 31 May 2005 17:16, Ian Pratt wrote:
> > I had a chance to run a couple of the netperf tests with
> > xenoprofile.  I am still having some trouble with
> > multi-domain profiles (probably user error), but I have been
> > able to profile dom0 while running 2 types of tests.  I was
> > surprised to see as much as 50% cpu in hypervisor on these tests:
> >
> > netperf tcp_stream 16k msg size, dom1 -> dom2 dom0 is on
> > cpu0, HT thread 0, dom1 is on cpu1, HT thread 0,
> > dom2 is on cpu1, HT thread 1.
>
> Let's ignore the domU <-> domU results for the moment as we know
> about the problem with lack of batching in this scenario. Let's dig
> into the dom1 -> external.
>
> First off, are these figures just for CPU 0 HT 0? i.e. just dom0 so
> we don't see where time goes in the domU? How is idle time on the CPU
> reported?

Yes, this is just for CPU 0 HT 0.  DomU is pinned to its own cpu, which 
is CPU 1 HT 0.  

I have cpu util from polling xc_domain_get_cpu_usage() for both domains, 
which is (an exerpt from the whole run, in 3 second intervals):

 cpu0:  [100.4] d0-0[100.4]
 cpu2:  [045.1] d1-0[045.1]

 cpu0:  [100.0] d0-0[100.0]
 cpu2:  [045.1] d1-0[045.1]

 cpu0:  [099.6] d0-0[099.6]
 cpu2:  [045.1] d1-0[045.1]

 cpu0:  [101.3] d0-0[101.3]
 cpu2:  [045.3] d1-0[045.3]

 cpu0:  [099.7] d0-0[099.7]
 cpu2:  [045.1] d1-0[045.1]

 cpu0:  [099.7] d0-0[099.7]
 cpu2:  [045.0] d1-0[045.0]

This is fairly consistent for the whole test.

> Spending 18% of the time handling interrupts in Xen is surprisingy
> (at least to me).
>
> What interrupt rate are you observing? What are the default tg3
> interrupt coallescing settings? What interrupt rate do you get on
> native? Also, what hypercall rate are you seeing?
>
> (It would be good to put this in context of the rx/tx packet rates).

I don't have that data from this test, but I am queuing up another with 
sar, so I should have it soon.

I will also queue up a test with just baremetal linux so we can compare 
int rates, etc.

> Is the Ethernet NIC sharing an interrupt with the USB controller per
> chance?

Not as far as I can tell:

           CPU0
  1:          8        Phys-irq  i8042
  3:          0        Phys-irq  acpi
  4:       3031        Phys-irq  serial
 11:    6764395        Phys-irq  ohci_hcd
 12:         93        Phys-irq  i8042
 15:      38687        Phys-irq  ide1
 18:      39398        Phys-irq  qla2300
 22:      47905        Phys-irq  ioc0
 24:    6037311        Phys-irq  eth0
256:          7     Dynamic-irq  ctrl-if
257:     182396     Dynamic-irq  timer0
258:          0     Dynamic-irq  net-be-dbg
259:      83437     Dynamic-irq  blkif-backend
260:    1688517     Dynamic-irq  vif1.0

>
> Seeing find_domain_by_id and copy_from_user so high up the list is
> pretty surprising.

Yes.

-Andrew

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