Hi,
The upstream kernel has supported IIO free-running counters on Skylake
server. As of Skylake Server, there are a number of free running
counters in each IIO Box that collect counts of per-box IO clocks and
per-port Input/Output x BW/Utilization.
There are three types of IIO free-running counters on Skylake server:
1. IO CLOCKS counter: a clock of IIO box.
2. BANDWIDTH counters: count inbound(PCIe->CPU)/outbound(CPU->PCIe)
bandwidth.
3. UTILIZATION counters: count input/output utilization.
With these IIO free-running counters, we can get good observation for
IIO traffic on Skylake server. For example, we can see the IIO inbound
bandwidth (PCIe->CPU).
root@skx /sys/devices# perf stat -a -e
uncore_iio_free_running_2/bw_in_port0/
^C
Performance counter stats for 'system wide':
153.19 MiB uncore_iio_free_running_2/bw_in_port0/
8.037701069 seconds time elapsed
I propose to backport the patches which support IIO free-running
counters to 4.14 stable kernel.
perf/x86/intel/uncore: Introduce customized event_read() for client IMC
uncore
2da331465f44f9618abe8837d1a68405d550b66e
perf/x86/intel/uncore: Add new data structures for free running counters
927b2deb067b8b4753fc09c7a42092f43fc0c1f6
perf/x86/intel/uncore: Add infrastructure for free running counters
0e0162dfcd1fbe4c711ee86f24f966c318999603
perf/x86/intel/uncore: Support IIO free-running counters on SKX
0f519f0352e37e7d71bdce5559517c74a35f6e33
perf/x86/intel/uncore: Expose uncore_pmu_event*() functions
5a6c9d94e9ed7410142bc6fcb638a4db1895aa0c
perf/x86/intel/uncore: Clean up client IMC uncore
9aae1780e7e81e54edfb70ba33ead5b0b48be009
Thanks
Jin Yao
