RE: [PATCH 00/12] Cqm2: Intel Cache quality monitoring fixes

[Shivappa Vikas]

Hello Peterz/Andi,

On Thu, 2 Feb 2017, Luck, Tony wrote:

> > > 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.
> 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.

Assume we build support to monitor the existing resctrl CAT groups like Thomas 
suggested. For the perf interface would 
something like below seems reasonable or a disaster(given that we have a new -R 
option specific to the PMU/which works only on this PMU) ?

# mount -t resctrl resctrl /sys/fs/resctrl
# cd /sys/fs/resctrl
# mkdir p0 p1
# echo "L3:0=3;1=c" > /sys/fs/resctrl/p0/schemata
# echo "L3:0=3;1=3" > /sys/fs/resctrl/p1/schemata

Now monitor the group p1 using perf. perf would have a new option -R to monitor 
the resctrl groups. perf would still have a cqm event like today 
intel_cqm/llc_occupancy which supports however only one mode -R and not any of 
-C,-t,-G etc. So pretty much the -R works like a -G .. except that it works on 
the resctrl fs and not perf_cgroup.
PMU would have a flag to indicate the perf user mode to check only 
the llc_occupancy event is supported for the -R.

# perf stat -e intel_cqm/llc_occupancy -R p1

-Vikas

> -Tony