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1e6285699b
Perf can take minutes to parse an image when -ffunction-section is used. This is especially true with the kernel image when it is compiled this way, which is the arm64 default since the patcheset "Enable deadcode elimination at link time". Perf organize maps using a rbtree. Whenever perf finds a new symbols, it first searches this rbtree for the map it belongs to, by strcmp()'aring section names. When it finds the map with the right name, it uses it to add the symbol. With a usual image there aren't so many maps but when using -ffunction-section there's basically one map per function. With the kernel image that's north of 40,000 maps. For most symbols perf has to parses the entire rbtree to eventually create a new map and add it. Consequently perf spends most of the time browsing a rbtree that keeps getting larger. This performance fix introduces a secondary rbtree that indexes maps based on the section name. Signed-off-by: Eric Saint-Etienne <eric.saint.etienne@oracle.com> Reviewed-by: Dave Kleikamp <dave.kleikamp@oracle.com> Reviewed-by: David Aldridge <david.aldridge@oracle.com> Reviewed-by: Rob Gardner <rob.gardner@oracle.com> Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1542822679-25591-1-git-send-email-eric.saint.etienne@oracle.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com> |
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| Documentation | ||
| drivers | ||
| firmware | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
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| 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 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.