Re: [PATCH] powerpc/perf: Fix cycles/instructions as PM_CYC/PM_INST_CMPL in power10

On Thu, Jul 08, 2021 at 10:56:57PM +1000, Nicholas Piggin wrote:

Excerpts from Athira Rajeev's message of July 7, 2021 4:39 pm:

quoted

From: Athira Rajeev <redacted>

Power10 performance monitoring unit (PMU) driver uses performance
monitor counter 5 (PMC5) and performance monitor counter 6 (PMC6)
for counting instructions and cycles. Event used for cycles is
PM_RUN_CYC and instructions is PM_RUN_INST_CMPL. But counting of these
events in wait state is controlled by the CC56RUN bit setting in
Monitor Mode Control Register0 (MMCR0). If the CC56RUN bit is not
set, PMC5/6 will not count when CTRL[RUN] is zero.

What's the acutal bug here, can you explain a bit more? I thought
PM_RUN_CYC is supposed to be gated by the runlatch.

Would this renaming break compatibility with existing tools that
presume PM_RUN_CYC and PM_RUN_INST_CMPL exist generically?

PC