Hi,
On Tue, Oct 27, 2020 at 12:49 AM Alexander Shishkin
<alexander.shish...@linux.intel.com> wrote:
>
> Andi Kleen <a...@linux.intel.com> writes:
>
> > On Mon, Oct 26, 2020 at 11:19:37PM +0900, Namhyung Kim wrote:
> >> This patch just added a warning before running it. I'd really want to
> >> fix the kernel if possible but don't have a good idea. Thoughts?
> >
> > The easiest fix would be some multi threading in perf stat opening, then
> > then
> > extra latencies could be mostly hidden. One thread per group would probably
> > be overkill, but just a few threads would lower the penalty significantly.
> >
> > I think that would be better than this patch and it's likely not that much
> > more complicated, as this is already a lot of code.
> >
> >> +{
> >> + const char *known_sw_pmu[] = {
> >> + "software", "tracepoint", "breakpoint", "kprobe", "uprobe",
> >> "msr"
> >
> > That's a non scalable approach. New pmus get added regularly. It would be
> > better to
> > indicate this in a generic way from the kernel.
>
> That, and also, intel_pt is a software PMU and a few of its features
> depend on intel_pt/.../ being a group leader.
Thanks for the info, that's good to know.
So do you mean intel_pt requires other HW events in the same group?
Thanks
Namhyung
