Re: [patch 02/24] perfmon: base code

[stephane eranian]

On Thu, Nov 27, 2008 at 8:35 PM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote:
> Stephane,
>
> On Thu, 27 Nov 2008, stephane eranian wrote:
>
>> >> session is independent of each other. You can therefore measure different
>> >> things on different CPUs. Reservation is thus done independently for each
>> >> CPU, therefore we need a cpu bitmask  to track allocation.
>> >
>> > Ok. Question: if you do a one CPU wide session with perfom, can you
>> > still do thread monitoring on the same CPU ?
>> >
>> No. They are currently mutually exclusive.
>>
>> > If no, what prevents that a monitored thread is migrated to such a CPU ?
>> >
>> Nothing. AND you don't want to change affinity because you are monitoring.
>> So the current restriction is that cpu-wide and per-thread are
>> mutually exclusive.
>
> And how is this achieved ? Currently there seems nothing which
> prevents a per-thread vs. cpu-wide monitoring.
>
That's true, but that's because cpu-wide support is not included in the
patchset.
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