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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