Re: [Xen-devel] Xen & I/O in clusters - problems! New Information

[Rune Johan Andresen <runejoha@xxxxxxxxxxx>]

We tried to compile xen0 with CONFIG_E1000_NAPI = y and got the samre 
results between
two xen dom0 nodes. I am not sure if these interrupts tells anything:

Native Linux:


 CPU0
  0:   87290435          XT-PIC  timer
  1:          2          XT-PIC  keyboard
  2:          0          XT-PIC  cascade
  3:    7668994          XT-PIC  eth0
  7:          0          XT-PIC  ehci-hcd
  8:          1          XT-PIC  rtc
 10:          3          XT-PIC  usb-uhci
 11:     332088          XT-PIC  aic7xxx, aic7xxx, usb-uhci
 14:          1          XT-PIC  ide0
 15:          0          XT-PIC  libata
NMI:          0
ERR:          0


Xen Dom0:

          CPU0
  1:          2        Phys-irq  keyboard
 14:          3        Phys-irq  ide0
 18:     954304        Phys-irq  eth0
 24:       7313        Phys-irq  aic7xxx
 25:         30        Phys-irq  aic7xxx
128:          1     Dynamic-irq  misdirect
129:          0     Dynamic-irq  ctrl-if
130:     241914     Dynamic-irq  timer
131:          0     Dynamic-irq  timer_dbg, net-be-dbg
132:          0     Dynamic-irq  console
NMI:          0
ERR:          0

If you can see anything which is not normal behavior of xen please
tell us :)

Cheers,
Rune


On Oct 21, 2004, at 10:24 PM, Ian Pratt wrote:

> > Between two Xen dom0 domains (between two physical computers in the
> > cluster) we got these strange results:
> > (We use ttcp socketbuffsize, 10^4 -> 10^6)
> >
> > Kernel 2.6:
> > Xen Dom0 -> Xen Dom0: ca. 80 000 KB/s (?)
> >
> > Native Linux:
> > Native Linux -> Native Linux: ca. 114 000 KB/s
> >
> > What is new and strage is that Xen Dom0 use about 60% of the CPU when
> > transfering or receiving, while
> > Native Linux ony use 6-7%(!) It seems like we have a problem with the
> > DMA here(?). We use Xen 2.0,
> > Gigabit ethernet.
> dom0 to dom0 performance really shouldn't be any difference from
> native. It certainly isn't on any of our machines.
>
> The only thing I can think of is that something stupid might be
> happening with interrupts on your machines. Can you compare the
> rate that the relevant interrupts are going up in
> /proc/interrupts between xenLinux and native.
>
> There's no interrupt sharing or anything daft like that going on?
> Are you using NAPI on the native e1000 linux driver?
>
>
> Ian

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