Re: [Xen-users] VT-d "partial" success - passing DVB-S tuner to Windows DomU (based off previous thread of similar name!)

[Stephan Seitz <s.seitz@xxxxxxxxxxxx>]

Hi Daniel,

it's speculative, but have you additionally tried to use only one cpu
and pin that one to core?

domU:

# no SMP
vcpus = '1'
# second core
cpu = '1'

Daniel Kao schrieb:
> Hi Stephan,
>
> Thanks for the response.
>
> I actually tried leaving default settings and irqbalance was installed 
> by default in my CentOS 5.2 install.  Maybe I should try turning 
> irqbalance off?  It definitely seems to be irq-related.  :(
> 03:02pm root@vps-cluster-01:/root% service irqbalance status
> irqbalance (pid 3585) is running...
> 03:04pm root@vps-cluster-01:/root%
>
> Cheers,
> Daniel
>
> Stephan Seitz wrote:
> > Hi,
> >
> > I noticed similar behaviour of missing interrupts in domU's (well, 
> > PV/pci-
> > passthrough) if the dom0 is under load (sometimes only slightly above
> > idle has been enough).
> >
> > Leaving dom0 all cpu's (just the default settings) and installing 
> > irqbalance
> > in dom0 solved this issue.
> >
> > I don't know if it's of much use to you, but it's worth to try ;)
> >
> >
> > cheers,
> >
> > Stephan
> >
> >
> > Daniel Kao schrieb:
> > > Hi All,
> > >
> > > So I've got a DVB-S PCI Express card ($30 USD Twinhan AD-SE200 off 
> > > eBay) that's being passed via VT-d/pciback in Xen 3.2.1 under CentOS 
> > > 5.2 to a Windows XP SP3 which works! ... except for one small issue...
> > > Motherboard is an Intel DQ35JO that much people has had success with 
> > > and an Intel E8400 CPU.
> > > The issue is that when dealing with FTA MPEG-2 transport streams 
> > > (DVB-S based @ Galaxy 25 @ 97.0W), all is well until I start putting 
> > > a slight I/O (whether disk or otherwise) load under dom0.  The issue 
> > > is very similar and indicative of TV tuner cards and other PCI 
> > > devices which have poorly matched PCI latency timers.  Basically when 
> > > dom0 isn't under load, the DVB-S card and Windows XP SP3 works 
> > > great.  Once there's a slight load (I/O load; not CPU) in dom0, I get 
> > > continuity errors in the MPEG-2 packet transport stream.  Normally, 
> > > this is an issue with signal strength of the receiving satellite, but 
> > > this is not the issue.  These continuity errors are easily 
> > > reproducible.  All I have to do is log into my CentOS dom0's gnome 
> > > desktop via vnc (thru vncserver), launch the "Virtual Machine 
> > > Manager", and instantly the MPEG-2 packet stream will start seeing 
> > > continuity and stream errors.  The instant I close the "Virtual 
> > > Machine Manager" and log out of X, everything returns to normal.
> > > There's also a Dell PERC 5/i card (flashed to an LSI MegaRAID 8408E 
> > > firmware) that's running 8-750GB drives in RAID-5 which is visible in 
> > > dom0 as a file-server using samba.  And that's about it.
> > > I'm not sure where to start looking in resolving this issue but 
> > > issues of this type when searching other forums and answers seems to 
> > > be PCI latency related and resetting them on certain PCI bus devices 
> > > to fix continuity errors (even in a non-VM environment and straight 
> > > up Windows-based OS).  Doing an lspci -vvv on dom0 under a Xen 
> > > kernel, I noticed every single device on the PCI and PCIe has a 
> > > latency set to 0 which I find very odd (or is that normal for native 
> > > PCIe based chipsets?).  Also, I'm not even sure PCI latency affects 
> > > PCIe devices as they do PCI devices (especially since the Q35 chipset 
> > > is natively PCI-Express and all legacy PCI devices are being a 
> > > PCIe-to-PCI bridge).  Or... am I just barking up the wrong tree? ;)
> > > I can post a lspci -vvv if that would help.  Since the domU is HVM 
> > > and it's Windows XP, I've tried using the "PCI Latency Tool 3.1.2" 
> > > but the PCIe DVB-S card would not show in the list of PCI devices.  
> > > Other testing I've done, I started off using "ACPI Multiprocessor" as 
> > > the HAL, then dropped to the more stable "Standard PC" HAL (so going 
> > > back to the ACPI HAL means a re-install of the OS), and then 
> > > disabling ACPI and APIC and turning off PAE... etc.  It has no affect.
> > > Anyone have any ideas?  Thanks in advance!
> > >
> > > --
> > > Daniel Kao
> > > Übermind, Inc.
> > > Seattle, WA, U.S.A.
> > >
> > >
> > > ------------------------------------------------------------------------
> > >
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--
Stephan Seitz
Senior System Administrator

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