* [Qemu-devel] Performance counter
@ 2007-09-10 1:49 Peter Nguyen
2007-09-10 8:46 ` Filip Navara
0 siblings, 1 reply; 3+ messages in thread
From: Peter Nguyen @ 2007-09-10 1:49 UTC (permalink / raw)
To: qemu-devel
Hi,
I'm using qemu at the moment to run a system for debugging purposes. I
was wondering whether qemu does actually emulate the performance
counters on IA32. Every time i try to read the value out, it
consistently gives me zero even though i have written to the given model
specific register.
Thanks
Peter Nguyen
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] Performance counter
2007-09-10 1:49 [Qemu-devel] Performance counter Peter Nguyen
@ 2007-09-10 8:46 ` Filip Navara
2007-09-10 15:15 ` Paul Brook
0 siblings, 1 reply; 3+ messages in thread
From: Filip Navara @ 2007-09-10 8:46 UTC (permalink / raw)
To: qemu-devel
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Hi,
the performance registers aren't implemented on QEMU.
Best regards,
Filip Navara
On 9/10/07, Peter Nguyen <peter.nguyen@adelaide.edu.au> wrote:
>
> Hi,
>
> I'm using qemu at the moment to run a system for debugging purposes. I
> was wondering whether qemu does actually emulate the performance
> counters on IA32. Every time i try to read the value out, it
> consistently gives me zero even though i have written to the given model
> specific register.
>
> Thanks
> Peter Nguyen
>
>
>
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [Qemu-devel] Performance counter
2007-09-10 8:46 ` Filip Navara
@ 2007-09-10 15:15 ` Paul Brook
0 siblings, 0 replies; 3+ messages in thread
From: Paul Brook @ 2007-09-10 15:15 UTC (permalink / raw)
To: qemu-devel; +Cc: Filip Navara
> > I'm using qemu at the moment to run a system for debugging purposes. I
> > was wondering whether qemu does actually emulate the performance
> > counters on IA32. Every time i try to read the value out, it
> > consistently gives me zero even though i have written to the given model
> > specific register.
>
> the performance registers aren't implemented on QEMU.
QEMU is not cycle accurate, nor does it emulate memory caches or have an
accurate TLB model, so I'm fairly sure we do can have provide meaningful
values for most of the counters.
Paul
^ permalink raw reply [flat|nested] 3+ messages in thread
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2007-09-10 1:49 [Qemu-devel] Performance counter Peter Nguyen
2007-09-10 8:46 ` Filip Navara
2007-09-10 15:15 ` Paul Brook
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