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Update benchmark results in README.md
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keithw committed Mar 13, 2012
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Expand Up @@ -143,21 +143,19 @@ Advice to distributors
A note on compiler flags: Mosh is security-sensitive code. When making
automated builds for a binary package, we recommend passing the option
`--enable-compile-warnings=error` to ./configure. On GNU/Linux with
gcc and a system boost, the package should compile cleanly with
-Werror. Please report a bug if it doesn't.
g++ or clang++, the package should compile cleanly with
`-Werror`. Please report a bug if it doesn't.

Mosh ships with a default optimization setting of `-O2`. Some
distributors have asked about changing this to `-Os` (which causes a
compiler to prefer space optimizations to time optimization). We have
benchmarked mosh with g++ 4.6 and clang++ 2.9 to see if `-Os` might be
preferable. In both cases, -Os did produce a smaller binary (by up to
40%, saving a few hundred kilobytes), but at a considerable cost to
mosh's performance -- about 28-31% for both compilers, or similar to a
typical net benefit from enabling optimization. While Mosh is not
especially CPU intensive and mostly sits idle when the user is not
typing, our recommendation to distributors would be to stay with the
default of `-O2` unless saving space on disk is particularly
important.
benchmarked with the included `src/examples/benchmark` program to test
this. The results are that `-O2` is 40% faster than `-Os` with g++ 4.6
on GNU/Linux, and 16% faster than `-Os` with clang++ 3.1 on Mac OS
X. In both cases, `-Os` did produce a smaller binary (by up to 40%,
saving almost 200 kilobytes on disk). While Mosh is not especially CPU
intensive and mostly sits idle when the user is not typing, we think
the results suggest that `-O2` (the default) is preferable.

More info
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