Re: [PATCH 0/5] alpha/perf: add ProfileMe sampling

[Peter Zijlstra]

On Wed, Oct 28, 2026 at 02:09:29PM -0400, Matt Turner wrote:
> The 21264 from EV67 on, and the 21364, have a second performance counter
> mode, ProfileMe, alongside the Aggregate mode that the driver uses today.
> An Aggregate mode sample reports the PC where the overflow interrupt was
> taken. On an EV7 that is anywhere from 15 instructions before to 12
> after the one that overflowed the counter, which makes perf annotate
> output close to useless. In ProfileMe mode the CPU picks one fetched
> instruction, follows it down the pipeline, and reports its PC along with
> what happened to it: whether it retired, whether it trapped and why,
> whether it was a mispredicted branch, stalled before map, or was killed
> on a wrong path, and what PCTR1 counted while it was in flight.

Isn't this the thing that ended up as AMD's IBS?