Re: [Xen-devel] [timer/ticks related] dom0 hang during boot on large 1TB system

["Jan Beulich" <JBeulich@xxxxxxxxxx>]

>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 22.12.09 14:35 >>>
>> And then it should be possible to simulate the problem quite easily on
>> a system with much less memory, by slowing down the scrub loop
>> artificially. If I find time before the holiday break I'll try to do that and
>> see if I can convince myself otherwise (as per above).
>> artificially
>
>That would be helpful, thanks. I'm particularly intrigued by how this could
>be seen for dom0 but not be a similar or worse issue for domU.

Simulating the issue indeed went without problem. What I'm seeing is
a Xen problem, though (as expected): Right around when scrubbing
starts there is a run through time_calibration(). During and after scrub,
none happen however, until Dom0 proceeded quite a bit into its
initialization (namely, past its delay loop calibration). It is only then
when regular (1 second interval) time_calibration() invocations resume.

One other irregular at the first glance thing is that the mentioned
very first run through time_calibration() does not seem to result in
running local_time_calibration() on CPU0. One invocation (apparently
independent of time_calibration()) happens right before Dom0 starts
executing.

Jan

(XEN) *** LOADING DOMAIN 0 ***
(XEN)  Xen  kernel: 64-bit, lsb, compat32
(XEN)  Dom0 kernel: 32-bit, PAE, lsb, paddr 0x2000 -> 0x496000
(XEN) PHYSICAL MEMORY ARRANGEMENT:
(XEN)  Dom0 alloc.:   0000000229000000->000000022a000000 (1936909 pages to be 
allocated)
(XEN) VIRTUAL MEMORY ARRANGEMENT:
(XEN)  Loaded kernel: 00000000c0002000->00000000c0496000
(XEN)  Init. ramdisk: 00000000c0496000->00000000c0759193
(XEN)  Phys-Mach map: 00000000c075a000->00000000c0ec1834
(XEN)  Start info:    00000000c0ec2000->00000000c0ec24b4
(XEN)  Page tables:   00000000c0ec3000->00000000c0ed1000
(XEN)  Boot stack:    00000000c0ed1000->00000000c0ed2000
(XEN)  TOTAL:         00000000c0000000->00000000c1000000
(XEN)  ENTRY ADDRESS: 00000000c0002000
(XEN) Dom0 has maximum 8 VCPUs
(XEN) tc
(XEN) ltc@4[32767:4]
(XEN) ltc@3[32767:3]
(XEN) ltc@7[32767:7]
(XEN) ltc@6[32767:6]
(XEN) Scrubbing Free RAM: ltc@2[32767:2]
(XEN) ltc@5[32767:5]
(XEN) ltc@1[32767:1]
(XEN) .....done.
(XEN) Xen trace buffers: disabled
(XEN) Std. Loglevel: All
(XEN) Guest Loglevel: All
(XEN) Xen is relinquishing VGA console.
(XEN) *** Serial input -> Xen (type 'CTRL-q' three times to switch input to 
DOM0)
(XEN) Freed 160kB init memory.
(XEN) ltc@0[0:0]



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