Re: smp guest questions

[Michael Tokarev <mjt@tls.msk.ru>]

Avi Kivity wrote:
> On 06/17/2009 11:38 AM, Michael Tokarev wrote:
>> After seeing words from Avi about that smp guests
>> are ok now, I descided to try.  And immediately
>> got a few questions.
>>
>> Running on a Phenom 9750 machine (PhenomI), AMD780G
>> chipset.  Host is 2.6.29 x86-64, qemu-kvm 0.10.5,
>> guests are linux with kvm paravirt bits enabled, also
>> dynticks (on both host and guest).
>>
>>
>> When booting a 2-CPU guest, I see in dmesg:
>>
>> PM-Timer running at invalid rate: 200% of normal - aborting.
>>
>> and indeed, in available_clocksource there's no pmtimer.
>> Should I be concerned?  It does not look healthy.
>>
> 
> It's a bug, please post guest details (kernel version, bitness).

The guest kernel is also 2.6.29[.5], but this time it's x86-32
(compiled for P4).  kvm userspace is also 32bits (historical) --
only host kernel is 64bit for now.  I'll try to do some more
experiments later today on a test machine (this is a production
box) -- "hopefully" that same issue will occur on another
machine :)

> Copying Marcelo.
> 
>>
>> Some time later, I see stuff like:
>>
>> hrtimer: interrupt too slow, forcing clock min delta to 47210997 ns
>>
>> Which reminds me issues I had with broken hpet (time goes
>> back-n-forth with similar messages shown in dmesg, but
>> about hpet not hrtimer).  Also does not look healthy.
>>
>>
>> I haven't seen either of the two messages above on any of
>> single-processor guests so far, at least with recent kernels
>> and kvm userspace, only on smp (2 cpu for now).
> 
> Please also post host /proc/cpuifo.

HOST cpuinfo (only for 4th core, other cores are similar):
processor	: 3
vendor_id	: AuthenticAMD
cpu family	: 16
model		: 2
model name	: AMD Phenom(tm) 9750 Quad-Core Processor
stepping	: 3
cpu MHz		: 1200.000
(yes ondemand cpufreq is in effect - nominal frequency is 2400.
I had no issues with cpufreq on this box so far, including all
the guests).
cache size	: 512 KB
physical id	: 0
siblings	: 4
core id		: 3
cpu cores	: 4
apicid		: 3
initial apicid	: 3
fpu		: yes
fpu_exception	: yes
cpuid level	: 5
wp		: yes
flags		: fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt pdpe1gb rdtscp lm 3dnowext 3dnow constant_tsc rep_good nonstop_tsc pni monitor cx16 lahf_lm cmp_legacy svm extapic cr8_legacy abm sse4a misalignsse 3dnowprefetch osvw ibs
bogomips	: 4812.67
TLB size	: 1024 4K pages
clflush size	: 64
cache_alignment	: 64
address sizes	: 48 bits physical, 48 bits virtual
power management: ts ttp tm stc 100mhzsteps hwpstate



cpuinfo on GUEST (also for only one CPU):

processor	: 1
vendor_id	: AuthenticAMD
cpu family	: 6
model		: 2
model name	: QEMU Virtual CPU version 0.10.5
stepping	: 3
cpu MHz		: 2405.894
cache size	: 512 KB
fdiv_bug	: no
hlt_bug		: no
f00f_bug	: no
coma_bug	: no
fpu		: yes
fpu_exception	: yes
cpuid level	: 2
wp		: yes
flags		: fpu de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 syscall lm pni hypervisor
bogomips	: 4811.78
clflush size	: 64
power management:


Thanks!

/mjt