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

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Date:   Thu, 2 Feb 2017 12:20:23 -0800 (PST)
From:   Shivappa Vikas <vikas.shivappa@...el.com>
To:     "Luck, Tony" <tony.luck@...el.com>
cc:     David Carrillo-Cisneros <davidcc@...gle.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Vikas Shivappa <vikas.shivappa@...ux.intel.com>,
        "Shivappa, Vikas" <vikas.shivappa@...el.com>,
        Stephane Eranian <eranian@...gle.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        x86 <x86@...nel.org>, "hpa@...or.com" <hpa@...or.com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "Yu, Fenghua" <fenghua.yu@...el.com>,
        "Kleen, Andi" <andi.kleen@...el.com>,
        "Anvin, H Peter" <h.peter.anvin@...el.com>
Subject: RE: [PATCH 00/12] Cqm2: Intel Cache quality monitoring fixes


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
>