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e7b60c5a0c
No need to load symbols in a DSO when injecting build-id. I guess the
reason was to check the DSO is a special file like anon files. Use some
helper functions in map.c to check them before reading build-id. Also
pass sample event's cpumode to a new build-id event.
It brought a speedup in the benchmark of 25 -> 21 msec on my laptop.
Also the memory usage (Max RSS) went down by ~200 KB.
# Running 'internals/inject-build-id' benchmark:
Average build-id injection took: 21.389 msec (+- 0.138 msec)
Average time per event: 2.097 usec (+- 0.014 usec)
Average memory usage: 8225 KB (+- 0 KB)
Committer notes:
Before:
$ perf stat -r5 perf bench internals inject-build-id > /dev/null
Performance counter stats for 'perf bench internals inject-build-id' (5 runs):
4,020.56 msec task-clock:u # 1.271 CPUs utilized ( +- 0.74% )
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
123,354 page-faults:u # 0.031 M/sec ( +- 0.81% )
7,119,951,568 cycles:u # 1.771 GHz ( +- 1.74% ) (83.27%)
230,086,969 stalled-cycles-frontend:u # 3.23% frontend cycles idle ( +- 1.97% ) (83.41%)
1,168,298,765 stalled-cycles-backend:u # 16.41% backend cycles idle ( +- 1.13% ) (83.44%)
11,173,083,669 instructions:u # 1.57 insn per cycle
# 0.10 stalled cycles per insn ( +- 1.58% ) (83.31%)
2,413,908,936 branches:u # 600.392 M/sec ( +- 1.69% ) (83.26%)
46,576,289 branch-misses:u # 1.93% of all branches ( +- 2.20% ) (83.31%)
3.1638 +- 0.0309 seconds time elapsed ( +- 0.98% )
$
After:
$ perf stat -r5 perf bench internals inject-build-id > /dev/null
Performance counter stats for 'perf bench internals inject-build-id' (5 runs):
2,379.94 msec task-clock:u # 1.473 CPUs utilized ( +- 0.18% )
0 context-switches:u # 0.000 K/sec
0 cpu-migrations:u # 0.000 K/sec
62,584 page-faults:u # 0.026 M/sec ( +- 0.07% )
2,372,389,668 cycles:u # 0.997 GHz ( +- 0.29% ) (83.14%)
106,937,862 stalled-cycles-frontend:u # 4.51% frontend cycles idle ( +- 4.89% ) (83.20%)
581,697,915 stalled-cycles-backend:u # 24.52% backend cycles idle ( +- 0.71% ) (83.47%)
3,659,692,199 instructions:u # 1.54 insn per cycle
# 0.16 stalled cycles per insn ( +- 0.10% ) (83.63%)
791,372,961 branches:u # 332.518 M/sec ( +- 0.27% ) (83.39%)
10,648,083 branch-misses:u # 1.35% of all branches ( +- 0.22% ) (83.16%)
1.61570 +- 0.00172 seconds time elapsed ( +- 0.11% )
$
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Original-patch-by: Stephane Eranian <eranian@google.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Link: https://lore.kernel.org/r/20201012070214.2074921-5-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.