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c8035a4961
Rather than using the first evsel in the matched events, try to find
the least shared non-tool evsel. The aim is to pick the first evsel
that typifies the metric within the list of metrics.
This addresses an issue where Default metric group metrics may lose
their counter value due to how the stat displaying hides counters for
default event/metric output.
For a metricgroup like TopdownL1 on an Intel Alderlake the change is,
before there are 4 events with metrics:
```
$ perf stat -M topdownL1 -a sleep 1
Performance counter stats for 'system wide':
7,782,334,296 cpu_core/TOPDOWN.SLOTS/ # 10.4 % tma_bad_speculation
# 19.7 % tma_frontend_bound
2,668,927,977 cpu_core/topdown-retiring/ # 35.7 % tma_backend_bound
# 34.1 % tma_retiring
803,623,987 cpu_core/topdown-bad-spec/
167,514,386 cpu_core/topdown-heavy-ops/
1,555,265,776 cpu_core/topdown-fe-bound/
2,792,733,013 cpu_core/topdown-be-bound/
279,769,310 cpu_atom/TOPDOWN_RETIRING.ALL/ # 12.2 % tma_retiring
# 15.1 % tma_bad_speculation
457,917,232 cpu_atom/CPU_CLK_UNHALTED.CORE/ # 38.4 % tma_backend_bound
# 34.2 % tma_frontend_bound
783,519,226 cpu_atom/TOPDOWN_FE_BOUND.ALL/
10,790,192 cpu_core/INT_MISC.UOP_DROPPING/
879,845,633 cpu_atom/TOPDOWN_BE_BOUND.ALL/
```
After there are 6 events with metrics:
```
$ perf stat -M topdownL1 -a sleep 1
Performance counter stats for 'system wide':
2,377,551,258 cpu_core/TOPDOWN.SLOTS/ # 7.9 % tma_bad_speculation
# 36.4 % tma_frontend_bound
480,791,142 cpu_core/topdown-retiring/ # 35.5 % tma_backend_bound
186,323,991 cpu_core/topdown-bad-spec/
65,070,590 cpu_core/topdown-heavy-ops/ # 20.1 % tma_retiring
871,733,444 cpu_core/topdown-fe-bound/
848,286,598 cpu_core/topdown-be-bound/
260,936,456 cpu_atom/TOPDOWN_RETIRING.ALL/ # 12.4 % tma_retiring
# 17.6 % tma_bad_speculation
419,576,513 cpu_atom/CPU_CLK_UNHALTED.CORE/
797,132,597 cpu_atom/TOPDOWN_FE_BOUND.ALL/ # 38.0 % tma_frontend_bound
3,055,447 cpu_core/INT_MISC.UOP_DROPPING/
671,014,164 cpu_atom/TOPDOWN_BE_BOUND.ALL/ # 32.0 % tma_backend_bound
```
Signed-off-by: Ian Rogers <irogers@google.com>
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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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 reStructuredText 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.