a6e4a4a14a
The hierarchy mode needs to setup output formats for each evsel.
Normally setup_sorting() handles this at the beginning, but it cannot
do that if data comes from a pipe since there's no evsel info before
reading the data. And then perf report cannot process the samples
in hierarchy mode and think as if there's no sample.
Let's check the condition and setup the output formats after reading
data so that it can find evsels.
Before:
$ ./perf record -o- true | ./perf report -i- --hierarchy -q
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.000 MB - ]
Error:
The - data has no samples!
After:
$ ./perf record -o- true | ./perf report -i- --hierarchy -q
[ perf record: Woken up 1 times to write data ]
[ perf record: Captured and wrote 0.000 MB - ]
94.76% true
94.76% [kernel.kallsyms]
94.76% [k] filemap_fault
5.24% perf-ex
5.24% [kernel.kallsyms]
5.06% [k] __memset
0.18% [k] native_write_msr
Acked-by: Ian Rogers <irogers@google.com>
Link: https://lore.kernel.org/r/20231025003121.2811738-1-namhyung@kernel.org
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
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.