Messages in this thread Patch in this message | | | From | Vikas Shivappa <> | Subject | [PATCH 01/14] x86/cqm: Intel Resource Monitoring Documentation | Date | Fri, 16 Dec 2016 15:12:55 -0800 |
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Add documentation of usage of cqm and mbm events, continuous monitoring, lazy and non-lazy monitoring.
Signed-off-by: Vikas Shivappa <vikas.shivappa@linux.intel.com> --- Documentation/x86/intel_rdt_mon_ui.txt | 91 ++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) create mode 100644 Documentation/x86/intel_rdt_mon_ui.txt
diff --git a/Documentation/x86/intel_rdt_mon_ui.txt b/Documentation/x86/intel_rdt_mon_ui.txt new file mode 100644 index 0000000..7d68a65 --- /dev/null +++ b/Documentation/x86/intel_rdt_mon_ui.txt @@ -0,0 +1,91 @@ +User Interface for Resource Monitoring in Intel Resource Director Technology + +Vikas Shivappa<vikas.shivappa@intel.com> +David Carrillo-Cisneros<davidcc@google.com> +Stephane Eranian <eranian@google.com> + +This feature is enabled by the CONFIG_INTEL_RDT_M Kconfig and the +X86 /proc/cpuinfo flag bits cqm_llc cqm_occup_llc cqm_mbm_total cqm_mbm_local + +Resource Monitoring +------------------- +Resource Monitoring includes cqm(cache quality monitoring) and +mbm(memory bandwidth monitoring) and uses the perf interface. A light +weight interface to enable monitoring without perf is enabled as well. + +CQM provides OS/VMM a way to monitor llc occupancy. It measures the +amount of L3 cache fills per task or cgroup. + +MBM provides OS/VMM a way to monitor bandwidth from one level of cache +to another. The current patches support L3 external bandwidth +monitoring. It supports both 'local bandwidth' and 'total bandwidth' +monitoring for the socket. Local bandwidth measures the amount of data +sent through the memory controller on the socket and total b/w measures +the total system bandwidth. + +To check the monitoring events enabled: + +# ./tools/perf/perf list | grep -i cqm +intel_cqm/llc_occupancy/ [Kernel PMU event] +intel_cqm/local_bytes/ [Kernel PMU event] +intel_cqm/total_bytes/ [Kernel PMU event] + +Monitoring tasks and cgroups using perf +--------------------------------------- +Monitoring tasks and cgroup is like using any other perf event. + +#perf stat -I 1000 -e intel_cqm_llc/local_bytes/ -p PID1 + +This will monitor the local_bytes event of the PID1 and report once +every 1000ms + +#mkdir /sys/fs/cgroup/perf_event/p1 +#echo PID1 > /sys/fs/cgroup/perf_event/p1/tasks +#echo PID2 > /sys/fs/cgroup/perf_event/p1/tasks + +#perf stat -I 1000 -e intel_cqm_llc/llc_occupancy/ -a -G p1 + +This will monitor the llc_occupancy event of the perf cgroup p1 in +interval mode. + +Hierarchical monitoring should work just like other events and users can +also monitor a task with in a cgroup and the cgroup together, or +different cgroups in the same hierarchy can be monitored together. + +Continuous monitoring +--------------------- +A new file cont_monitoring is added to perf_cgroup which helps to enable +cqm continuous monitoring. Enabling this field would start monitoring of +the cgroup without perf being launched. This can be used for long term +light weight monitoring of tasks/cgroups. + +To enable continuous monitoring of cgroup p1. +#echo 1 > /sys/fs/cgroup/perf_event/p1/perf_event.cqm_cont_monitoring + +To disable continuous monitoring of cgroup p1. +#echo 0 > /sys/fs/cgroup/perf_event/p1/perf_event.cqm_cont_monitoring + +To read the counters at the end of monitoring perf can be used. + +LAZY and NOLAZY Monitoring +-------------------------- +LAZY: +By default when monitoring is enabled, the RMIDs are not allocated +immediately and allocated lazily only at the first sched_in. +There are 2-4 RMIDs per logical processor on each package. So if a dual +package has 48 logical processors, there would be upto 192 RMIDs on each +package = total of 192x2 RMIDs. +There is a possibility that RMIDs can runout and in that case the read +reports an error since there was no RMID available to monitor for an +event. + +NOLAZY: +When user wants guaranteed monitoring, he can enable the 'monitoring +mask' which is basically used to specify the packages he wants to +monitor. The RMIDs are statically allocated at open and failure is +indicated if RMIDs are not available. + +To specify monitoring on package 0 and package 1: +#echo 0-1 > /sys/fs/cgroup/perf_event/p1/perf_event.cqm_mon_mask + +An error is thrown if packages not online are specified. -- 1.9.1
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