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Data may have lots of overlapping mmaps. The regular insert adds at the end and relies on a later sort. For data with overlapping mappings the sort will happen during a subsequent maps__find or __maps__fixup_overlap_and_insert, there's never a period where the inserted maps buffer up and a single sort happens. To avoid back to back sorts, maintain the sort order when fixing up and inserting. Previously the first_ending_after search was O(log n) where n is the size of maps, and the insert was O(1) but because of the continuous sorting was becoming O(n*log(n)). With maintaining sort order, the insert now becomes O(n) for a memmove. For a perf report on a perf.data file containing overlapping mappings the time numbers are: Before: real 0m5.894s user 0m5.650s sys 0m0.231s After: real 0m0.675s user 0m0.454s sys 0m0.196s Signed-off-by: Ian Rogers <irogers@google.com> Reviewed-by: James Clark <james.clark@arm.com> Cc: Steinar H . Gunderson <sesse@google.com> Signed-off-by: Namhyung Kim <namhyung@kernel.org> Link: https://lore.kernel.org/r/20240521165109.708593-4-irogers@google.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 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.