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When a filtered column is not present in the sort order, profiles become arbitrary broken. Filtered and non-filtered entries are collapsed together, and the filtered-by field ends up with a random value (either from a filtered or non-filtered entry). If we end up with filtered entry/value, then the whole collapsed entry will be filtered out and will be missing in the profile. If we end up with non-filtered entry/value, then the overhead value will be wrongly larger (include some subset of filtered out samples). This leads to very confusing profiles. The problem is hard to notice, and if noticed hard to understand. If the filter is for a single value, then it can be fixed by adding the corresponding field to the sort order (provided user understood the problem). But if the filter is for multiple values, it's impossible to fix b/c there is no concept of binary sorting based on filter predicate (we want to group all non-filtered values in one bucket, and all filtered values in another). Examples of affected commands: perf report --tid=123 perf report --sort overhead,symbol --comm=foo,bar Fix this by considering filtered status as the highest priority sort/collapse predicate. As a side effect this effectively adds a new feature of showing profile where several lines are combined based on arbitrary filtering predicate. For example, showing symbols from binaries foo and bar combined together, but not from other binaries; or showing combined overhead of several particular threads. Signed-off-by: Dmitry Vyukov <dvyukov@google.com> Link: https://lore.kernel.org/r/359dc444ce94d20e59d3a9e360c36fbeac833a04.1736927981.git.dvyukov@google.com Signed-off-by: Namhyung Kim <namhyung@kernel.org> |
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| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .clippy.toml | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.