mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-12-24 22:48:38 +07:00
87 lines
2.3 KiB
Plaintext
87 lines
2.3 KiB
Plaintext
|
Intel Branch Trace Store
|
||
|
|
========================
|
||
|
|
|
||
|
|
Overview
|
||
|
|
========
|
||
|
|
|
||
|
|
Intel BTS could be regarded as a predecessor to Intel PT and has some
|
||
|
|
similarities because it can also identify every branch a program takes. A
|
||
|
|
notable difference is that Intel BTS has no timing information and as a
|
||
|
|
consequence the present implementation is limited to per-thread recording.
|
||
|
|
|
||
|
|
While decoding Intel BTS does not require walking the object code, the object
|
||
|
|
code is still needed to pair up calls and returns correctly, consequently much
|
||
|
|
of the Intel PT documentation applies also to Intel BTS. Refer to the Intel PT
|
||
|
|
documentation and consider that the PMU 'intel_bts' can usually be used in
|
||
|
|
place of 'intel_pt' in the examples provided, with the proviso that per-thread
|
||
|
|
recording must also be stipulated i.e. the --per-thread option for
|
||
|
|
'perf record'.
|
||
|
|
|
||
|
|
|
||
|
|
perf record
|
||
|
|
===========
|
||
|
|
|
||
|
|
new event
|
||
|
|
---------
|
||
|
|
|
||
|
|
The Intel BTS kernel driver creates a new PMU for Intel BTS. The perf record
|
||
|
|
option is:
|
||
|
|
|
||
|
|
-e intel_bts//
|
||
|
|
|
||
|
|
Currently Intel BTS is limited to per-thread tracing so the --per-thread option
|
||
|
|
is also needed.
|
||
|
|
|
||
|
|
|
||
|
|
snapshot option
|
||
|
|
---------------
|
||
|
|
|
||
|
|
The snapshot option is the same as Intel PT (refer Intel PT documentation).
|
||
|
|
|
||
|
|
|
||
|
|
auxtrace mmap size option
|
||
|
|
-----------------------
|
||
|
|
|
||
|
|
The mmap size option is the same as Intel PT (refer Intel PT documentation).
|
||
|
|
|
||
|
|
|
||
|
|
perf script
|
||
|
|
===========
|
||
|
|
|
||
|
|
By default, perf script will decode trace data found in the perf.data file.
|
||
|
|
This can be further controlled by option --itrace. The --itrace option is
|
||
|
|
the same as Intel PT (refer Intel PT documentation) except that neither
|
||
|
|
"instructions" events nor "transactions" events (and consequently call
|
||
|
|
chains) are supported.
|
||
|
|
|
||
|
|
To disable trace decoding entirely, use the option --no-itrace.
|
||
|
|
|
||
|
|
|
||
|
|
dump option
|
||
|
|
-----------
|
||
|
|
|
||
|
|
perf script has an option (-D) to "dump" the events i.e. display the binary
|
||
|
|
data.
|
||
|
|
|
||
|
|
When -D is used, Intel BTS packets are displayed.
|
||
|
|
|
||
|
|
To disable the display of Intel BTS packets, combine the -D option with
|
||
|
|
--no-itrace.
|
||
|
|
|
||
|
|
|
||
|
|
perf report
|
||
|
|
===========
|
||
|
|
|
||
|
|
By default, perf report will decode trace data found in the perf.data file.
|
||
|
|
This can be further controlled by new option --itrace exactly the same as
|
||
|
|
perf script.
|
||
|
|
|
||
|
|
|
||
|
|
perf inject
|
||
|
|
===========
|
||
|
|
|
||
|
|
perf inject also accepts the --itrace option in which case tracing data is
|
||
|
|
removed and replaced with the synthesized events. e.g.
|
||
|
|
|
||
|
|
perf inject --itrace -i perf.data -o perf.data.new
|