likwid-perfctr(1)
NAME
likwid-perfctr - configure and read out hardware performance counters on x86 CPUs
SYNOPSIS
likwid-perfctr [-vhHmaief] [-c core_list] [-C core_list_for_pinning] [-g performance_group or performance_event_string] [-t timeline_frequency] [-S monitoring_time] [-T group_switch_frequency] [-V verbosity] [-M access_mode] [-o output_file] [-s skip_mask] [-E search_str]
DESCRIPTION
likwid-perfctr is a lightweight command line application to configure and read out hardware performance monitoring data on supported x86 processors. It can measure either as wrapper without changing the measured application or with marker API functions inside the code, which will turn on and off the counters. There are preconfigured performance groups with useful event sets and derived metrics. Additionally, arbitrary events can be measured with custom event sets. The marker API can measure multiple named regions and the results are accumulated over multiple region calls.
OPTIONS
-v, --version
prints version information to standard output, then exits.
-h, --help
prints a help message to standard output, then exits.
-H prints group help message (use together with -g switch).
-V <level>, --verbose <level>
verbose output during execution for debugging. 0 for only
errors, 1 for informational output, 2 for detailed output and 3
for developer output
-m run in marker API mode
-a print available performance groups for current processor, then
exit.
-e print available counters and performance events of current
processor.
-o, --output <filename>
store all output to a file instead of stdout. For the filename
the following placeholders are supported: %j for PBS_JOBID, %r
for MPI RANK (only Intel MPI at the moment), %h host name and %p
for process pid. The placeholders must be separated by
underscore as, e.g., -o test_%h_%p. You must specify a suffix to
the filename. For txt the output is printed as is to the file.
Other suffixes trigger a filter on the output. Available
filters are csv (comma separated values) and xml at the moment.
-O print output in CSV format (conform to RFC 4180, see
https://tools.ietf.org/html/rfc4180 for details).
-i, --info
print cpuid information about processor and about Intel
Performance Monitoring features, then exit.
-c <cpu expression>
specify a numerical list of processors. The list may contain
multiple items, separated by comma, and ranges. For example
0,3,9-11.
-C <cpu expression>
specify a numerical list of processors. The list may contain
multiple items, separated by comma, and ranges. For example
0,3,9-11. This variant will also pin the threads to the cores.
Also logical numberings can be used.
-g, --group <performance group> or <performance event set string>
specify which performance group to measure. This can be one of
the tags output with the -a flag. Also a custom event set can
be specified by a comma separated list of events. Each event has
the format eventId:register with the the register being one of a
architecture supported performance counter registers.
-t <frequency of measurements>
timeline mode for time resolved measurements. The time unit must
be given on command line, e.g. 4s, 500ms or 900us.
-S <waittime between measurements>
End-to-end measurement using likwid-perfctr but sleep instead of
executing an application. The time unit must be given on command
line, e.g. 4s, 500ms or 900us.
-T <time between group switches>
Frequency to switch groups if multiple are given on commandline,
default is 2s. Value is ignored for a single event set and
default frequency of 30s is used to catch overflows. The time
unit must be given on command line, e.g. 4s, 500ms or 900us.
-s, --skip <mask>
Specify skip mask as HEX number. For each set bit the
corresponding thread is skipped.
-f, --force
Force writing of registers even if they are in use.
-E <search_str>
Print only events and corresponding counters matching
<search_str>
EXAMPLE
Because likwid-perfctr measures on processors and not single
applications it is necessary to ensure that processes and threads are
pinned to dedicated resources. You can either pin the application
yourself or use the builtin pin functionality.
1. As wrapper with performance group:
likwid-perfctr -C 0-2 -g TLB ./cacheBench -n 2 -l 1048576 -i 100 -t
Stream
The parent process is pinned to processor 0, Thread 0 to processor 1
and Thread 1 to processor 2.
2. As wrapper with custom event set on AMD:
likwid-perfctr -C 0-4 -g
INSTRUCTIONS_RETIRED_SSE:PMC0,CPU_CLOCKS_UNHALTED:PMC3 ./cacheBench
It is specified that the event INSTRUCTIONS_RETIRED_SSE is measured on
counter PMC0 and the event CPU_CLOCKS_UNHALTED on counter PMC3. It is
possible calculate the run time of all threads based on the
CPU_CLOCKS_UNHALTED event. If you want this you have to include this
event in your custom event string as shown above.
3. As wrapper with custom event set on Intel:
likwid-perfctr -C 0 -g
INSTR_RETIRED_ANY:FIXC0,CPU_CLK_UNHALTED_CORE:FIXC1,UNC_L3_LINES_IN_ANY:UPMC0
./stream-icc
On Intel processors fixed events are measured on dedicated counters.
These are INSTR_RETIRED_ANY and CPU_CLK_UNHALTED_CORE. If you
configure these fixed counters, likwid-perfctr will calculate the run
time and CPI metrics for your run.
4. Using the marker API to measure only parts of your code (this can
be used both with groups or custom event sets):
likwid-perfctr -m -C 0-4 -g
INSTRUCTIONS_RETIRED_SSE:PMC0,CPU_CLOCKS_UNHALTED:PMC3 ./cacheBench
You have to link you code against liblikwid.so and use the marker API
calls. Examples can be found in examples folder
/usr/share/likwid/examples. The following code snippet shows the
necessary calls:
#include <likwid.h>
/* only one thread calls init */
LIKWID_MARKER_INIT;
/* Must be called by each thread the should
* perform measurements.
* If you place it in the same parallel
* region as LIKWID_MARKER_START, perform a
* barrier between the statements to avoid
* timing problems.
*/
LIKWID_MARKER_THREADINIT;
/* If you run the code region only once, register
* the region tag previously to reduce the overhead
* of START and STOP calls. Call it once for each
* thread in parallel environment.
* Note: No whitespace characters are allowed in the region tags
* This call is optional, START will do the same operations.
*/
LIKWID_MARKER_REGISTER("name");
/* Start measurement
* Note: No whitespace characters are allowed in the region tags
*/
LIKWID_MARKER_START("name");
/*
* Your code to be measured is here
* You can also nest named regions
* No whitespaces are allowed in the region names!
*/
LIKWID_MARKER_STOP("name");
/* If you want to measure multiple groups/event sets
* Switches through groups in round-robin fashion
*/
LIKWID_MARKER_SWITCH;
/* Finally */
LIKWID_MARKER_CLOSE;
5. Using likwid in timeline mode:
likwid-perfctr -c 0-3 -g FLOPS_DP -t 300ms ./cacheBench > out.txt
This will read out the counters every 300ms on physical cores 0-3 and
write the results to out.txt. The application is not pinned to the
CPUs. The output syntax of the timeline mode is for custom event sets:
<groupID> <numberOfEvents> <numberOfThreads> <Timestamp>
<Event1_Thread1> <Event2_Thread1> ... <Event1_Thread2> ...
<EventN_ThreadM>
For performance groups with metrics: <groupID> <numberOfMetrics>
<numberOfThreads> <Timestamp> <Metric1_Thread1> <Metric2_Thread1> ...
<Metric1_Thread2> ...<MetricN_ThreadM>
For timeline mode there is a frontend application likwid-perfscope(1),
which enables live plotting of selected events. Please be aware that
with high frequencies (<100ms), the values differ from the real results
but the behavior of them is valid.
6. Using likwid in stethoscope mode:
likwid-perfctr -c 0-3 -g FLOPS_DP -S 2s
This will start the counters and read them out after 2s on physical
cores 0-3 and write the results to stdout.
7. Using likwid with counter options:
likwid-perfctr -c S0:1@S1:1 -g LLC_LOOKUPS_DATA_READ:CBOX0C0:STATE=0x9
./cacheBench
This will program the counter CBOX0C0 (the counter 0 of the LLC cache
box 0) to measure the event LLC_LOOKUPS_DATA_READ and filter the
increments by the state of a cacheline. STATE=0x9 for this event means
all <invalid> and <modified> cachelines. Which options are allowed for
which box is listed in LIKWID's html documentation. The values for the
options can be found in the vendors performance monitoring
documentations. Likwid measures the first CPU of socket 0 and the first
CPU of socket 1. See likwid-pin(1) for details regarding the cpu
expressions. For more code examples have a look at the likwid WIKI
pages and LIKWID's html documentation.
AUTHOR
Written by Thomas Roehl <thomas.roehl@googlemail.com>.
BUGS
Report Bugs on <https://github.com/RRZE-HPC/likwid/issues>.
SEE ALSO
likwid-topology(1), likwid-perfscope(1), likwid-pin(1), likwid-bench(1)
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