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When using perf to profile large binaries, _bfd_dwarf2_find_nearest_line() becomes a hotspot, as perf wants to get line number information (for inline-detection purposes) for each and every sample. In Chromium in particular (the content_shell binary), this entails going through 475k address ranges, which takes a long time when done repeatedly. Add a radix-256 trie over the address space to quickly map address to compilation unit spaces; for content_shell, which is 1.6 GB when some (but not full) debug information turned is on, we go from 6 ms to 0.006 ms (6 µs) for each lookup from address to compilation unit, a 1000x speedup. There is a modest RAM increase of 180 MB in this binary (the existing linked list over ranges uses about 10 MB, and the entire perf job uses between 2–3 GB for a medium-size profile); for smaller binaries with few ranges, there should be hardly any extra RAM usage at all.
README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.