Messages in this thread | | | Subject | Re: [Perfctr-devel] RE: [perfmon] Re: quick overview of the perfmon2 interface | From | Bryan O'Sullivan <> | Date | Wed, 25 Jan 2006 14:46:43 -0800 |
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On Wed, 2006-01-25 at 14:28 -0800, Stephane Eranian wrote:
> So it would help if you could > name the extended features you referring to.
I'm dubious about the hands-off buffer format in general. Does this mean that userspace needs to modprobe a specific set of modules in order to do normal sampling? If so, how do you work around the need for users to be root in order to use these interfaces?
> And perfmon > does allow it to continue working using almost all of its kernel code. > This is leveraging the custom sampling buffer format support in perfmon. > So you can say this is an extended feature that adds complexity. > But OTOH, this is one elegant way of supporting an existing interface > without breaking all the tools.
So are you saying that part of the existing oprofile code can be deleted if perfmon is merged, and that userspace won't notice?
> We were able to proide this support > with a few hundred lines of code without hacking the regular sampling > format. Instead we simply created a dedicated PEBS format as a kernel module.
Does this mean I can't sample the PMCs on a P4 if I don't have the special PEBS module loaded? Do I need to be root to do that?
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