Re: [Xen-devel] boot_cpu_data differs between Xen hypervisor boot and normal pv_ops kernel boot

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 03/31/2010 08:29 AM, Naresh Rapolu wrote:
> When I looked into the source code,  
> arch/x86/kernel/cpu/perf_event.c,   at run-time boot_cpu_data  
> structure seems to differ  in these two forms of booting.
> Due to this, Iam not able to use the hardware performance counters in  
> my Xeon 5530 processor  as  hardware events(cache-misses etc) are 
> being disabled.
> Is there any reason for this ?
The PMU hardware features are not virtualized, and are not available to 
guest domains.  I don't think Xen has much of a useful API to expose 
these features, though oprofile was working at one point.
I agree it would be very useful to work out how to get good "perf" 
support in a Xen domain.
(Stephen: It might be an interesting SoC project.)

    J

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