Software Tuning, Performance Optimization & Platform Monitoring
Discussion around monitoring and software tuning methodologies, Performance Monitoring Unit (PMU) of Intel microprocessors, and platform monitoring
1628 Discussions

Haswell PMU HW doesn't support sampling/overflow-interrupts (LBR)???

New Contributor I

CPU: E5-2699 v3 (Haswell)

Linux Kernel: 4.9.11-1


I'm attempting to sample code blocks associated with high cpu usage on a Haswell box using its Last Branch Record (LBR) feature but I'm getting this error:

# perf record -b -e cycles:u -p <PID>

PMU Hardware doesn't support sampling/overflow-interrupts

However, this same command works w/o issue on IvyBridge and an eval Skylake, even on an earlier kernel release (CentOS 7.1 - 3.10.0-229). Interestingly, when I execute "dmesg | grep -i pebs" on these hosts, I get the following output:

IvyBridge: Performance Events: PEBS fmt1+, 16-deep LBR, IvyBridge events, full-width counters, Intel PMU driver.

Haswell: Performance Events: PEBS fmt2+, Haswell events, full-width counters, Intel PMU driver.

Broadwell: Performance Events: PEBS fmt2+, generic architected perfmon, full-width counters, Intel PMU driver.

Skylake: Performance Events: PEBS fmt3+, 32-deep LBR, Skylake events, full-width counters, Intel PMU driver.

Only the hosts where the LBR information is specified will the LBR sampling work. Is this some bug with that particular tick-tock of HSW/BDW and LBR support?

0 Kudos
0 Replies