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
*netz-haut* e.K.
multimediale kommunikation
zweierweg 22
97074 würzburg
fon: +49 931 2876247
fax: +49 931 2876248
web: www.netz-haut.de <http://www.netz-haut.de/>
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