Ubuntu Manpage: likwid-bench - low-level benchmark suite and microbenchmarking framework

NAME

       likwid-bench - low-level benchmark suite and microbenchmarking framework

SYNOPSIS

       likwid-bench  [-hap]  [-t  <testname>]  [-s  <min_time>]  [-w <workgroup_expression>] [-l <testname>] [-d
       <delimiter>] [-i <iterations>]

DESCRIPTION

       likwid-bench is a  benchmark  suite  for  low-level  (assembly)  benchmarks  to  measure  bandwidths  and
       instruction  throughput  for  specific  instruction code on x86 systems. The currently included benchmark
       codes include common data access patterns like load and store but also calculations like vector triad and
       sum.  likwid-bench includes architecture specific benchmarks for x86, x86_64 and x86 for Intel  Xeon  Phi
       coprocessors.  The  performance  values  can  either  be  calculated  by  likwid-bench  or measured using
       performance counters by using likwid-perfctr as a  wrapper  to  likwid-bench.   This  requires  to  build
       likwid-bench with instrumentation enabled in config.mk.

OPTIONS

       -h     prints a help message to standard output, then exits.

       -a     list available benchmark codes for the current system.

       -p     list available thread domains.

       -s <min_time>
              Run  the  benchmark for at least <min_time> seconds.  The amount of iterations is determined using
              this value. Default: 1 second.

       -t <testname>
              Name of the benchmark code to run (mandatory).

       -w <workgroup_expression>
              Specify the affinity domain, thread count and data set  size  for  the  current  benchmarking  run
              (mandatory).

       -l <testname>
              list properties of a benchmark code.

       -i <iterations>
              Set the number of iterations per thread (optional)

WORKGROUP SYNTAX

       <thread_domain>:<size>  [:<num_threads>[:<chunk_size>:<stride>]]  [-<streamId>:<domain_id>]  with size in
       kB, MB or GB. The <thread_domain> defines where the threads are placed.  <size> is  the  total  data  set
       size for the benchmark, the allocated vectors in memory sum up to this size.  <num_threads> specifies how
       many  threads  are  used  in  the  <thread_domain>.   Threads are always placed using a compact policy in
       likwid-bench.  This means that per default all SMT threads are used. Optionally similar a the  expression
       based  syntax  in  likwid-pin  a  <chunk_size>  and <stride> can be provided. Optionally for every stream
       (array, vector) the placement can  be  controlled.  Per  default  all  arrays  are  placed  in  the  same
       <thread_domain> the threads are running in. To place the data in a different domain for every stream of a
       benchmark  case  (the  total  number of streams can be acquired by the -l option) the domain to place the
       data in can be specified. Multiple streams are comma separated. Either the placement is provided  or  all
       streams    have    to    be    explicitly    placed.    Please    refer    to    the    Wiki   pages   on
       http://code.google.com/p/likwid/wiki/LikwidBench for further details and examples on usage.

EXAMPLE

1. Run the copy benchmark on socket 0 ( S0 ) with a total data set size of 100kB.

likwid-bench -t copy -w S0:100kB

Since no <num_threads> is given in the workload expression, each core of socket 0 gets one thread. The
workload is split up between all threads and the number of iterations is determined automatically.

2. Run the triad benchmark code with explicitly 100 iterations per thread with 2 threads on the socket 0
( S0 ) and a data size of 1GB.

likwid-bench -t triad -i 100 -w S0:1GB:2:1:2

Assuming socket 0 ( S0 ) has 2 physical cores with SMT enabled, hence in total 4 hardware threads, one
thread is assigned to each physical core of socket 0.

3. Run the update benchmark on socket 0 ( S0 ) with a workload of 100kB and on socket 1 ( S1 ) with the
same workload.

likwid-bench -t update -w S0:100kB -w S1:100kB

The results of both workgroups are combinded for the output. Hence the workload in each workgroup
expression should have the same size.

4. Run the copy benchmark but measure the memory traffic with likwid-perfctr. The option
INSTRUMENT_BENCH in config.mk needs to be true at compile time to use that feature.

likwid-perfctr -c E:S0:4 -g MEM -m likwid-bench -t update -w S0:100kB

likwid-perfctr will configure and start the performance counters on socket 0 ( S0 ) with 4 threads prior
to the execution of likwid-bench. The performance counters are read right before and after running the
benchmarking code to minimize the interferences of the measurement.

5. Run the copy benchmark and place the data on another socket

likwid-bench -t copy -w S0:1GB:10:1:2-0:S1,1:S1

Stream id 0 and 1 are placed in thread domains S1, which is socket 1. This can be verified as the
initialization threads output where they are running.

AUTHOR

       Written by Thomas Roehl <thomas.roehl@googlemail.com>.

BUGS

       Report Bugs on <https://github.com/RRZE-HPC/likwid/issues>.