Messages in this thread | | | From | "Luck, Tony" <> | Subject | RE: [PATCH 00/12] Cqm2: Intel Cache quality monitoring fixes | Date | Thu, 2 Feb 2017 19:33:15 +0000 |
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>> Nice to have: >> 1) Readout using "perf(1)" [subset of modes that make sense ... tying monitoring >> to resctrl file system will make most command line usage of perf(1) close to impossible. > > > We discussed this offline and I still disagree that it is close to > impossible to use perf and perf_event_open. In fact, I think it's very > simple :
Maybe s/most/many/ ?
The issue here is that we are going to define which tasks and cpus are being monitored *outside* of the perf command. So usage like:
# perf stat -I 1000 -e intel_cqm/llc_occupancy {command}
are completely out of scope ... we aren't planning to change the perf(1) command to know about creating a CQM monitor group, assigning the PID of {command} to it, and then report on llc_occupancy.
So perf(1) usage is only going to support modes where it attaches to some monitor group that was previously established. The "-C 2" option to monitor CPU 2 is certainly plausible ... assuming you set up a monitor group to track what is happening on CPU 2 ... I just don't know how perf(1) would know the name of that group.
Vikas is pushing for "-R rdtgroup" ... though our offline discussions included overloading "-g" and have perf(1) pick appropriately from cgroups or rdtgroups depending on event type.
-Tony
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