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| LIKWID-FEATURES(1) |
General Commands Manual |
LIKWID-FEATURES(1) |
NAME¶
likwid-features - print and manipulate cpu features like hardware prefetchers
SYNOPSIS¶
likwid-features [-vhal] [-c cpus] [-e
taglist] [-d taglist]
DESCRIPTION¶
likwid-features is a command line application to print the flags in the
model specific register (MSR) MSR_IA32_MISC_ENABLE on Intel x86 processors. On
Core2 and later processors it can be used to toggle the hardware prefetch
flags. It does not work on AMD processors. For a documentation what flags are
supported on which processor refer to the Intel Software Developer's Manual
Volume 3B, Table B.2 and
https://software.intel.com/en-us/articles/disclosure-of-hw-prefetcher-control-on-some-intel-processors.
The MSR are set individually for every core. The following hardware
prefetchers can be toggled:
- •
- HW_PREFETCHER: Hardware prefetcher.
- •
- CL_PREFETCHER: Adjacent cache line prefetcher.
- •
- DCU_PREFETCHER: When the DCU prefetcher detects multiple loads from
the same line done within a time limit, the DCU prefetcher assumes the
next line will be required. The next line is prefetched in to the L1 data
cache from memory or L2.
- •
- IP_PREFETCHER: The IP prefetcher is an L1 data cache prefetcher.
The IP prefetcher looks for sequential load history to determine whether
to prefetch the next expected data into the L1 cache from memory or L2.
OPTIONS¶
- -v
- prints version information to standard output, then exits.
- -h
- prints a help message to standard output, then exits.
- -a
- List out the names of all detected features
- -l
- Print the state of all features for the given CPUs
- -c cpus
- set on which processor cores the MSR should be read and written. Syntax
according to likwid-pin(1)
- -d HW_PREFETCHER | CL_PREFETCHER | DCU_PREFETCHER |
IP_PREFETCHER
- specify which prefetcher should be disabled. Argument can be a
comma-separated list.
- -e HW_PREFETCHER | CL_PREFETCHER | DCU_PREFETCHER |
IP_PREFETCHER
- specify which prefetcher should be enabled. Argument can be a
comma-separated list.
AUTHOR¶
Written by Thomas Röhl <thomas.Roehl@gmail.com>.
