Messages in this thread | | | Date | Tue, 07 Apr 2015 10:07:13 +0300 | From | Boaz Harrosh <> | Subject | Re: Why not build kernel with -O3 |
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On 04/07/2015 09:43 AM, Mike Galbraith wrote: > On Tue, 2015-04-07 at 11:37 +0800, Pengfei Yuan wrote: >> Hi, >> >> I have conducted some experiments to compare kernels built with -O2 >> and -O3. Here are the results: >> >> Application Performance O2 Performance O3 Improvement >> Apache 127814.14 req/s 130321.24 req/s 1.96% >> Nginx 537589.08 req/s 556723.32 req/s 3.56% >> MySQL 70661.38 tx/s 71008.47 tx/s 0.49% >> PostgreSQL 79763.39 tx/s 79535.59 tx/s -0.29% >> Redis 352547.47 op/s 405417.24 op/s 15.0% >> Memcached 844439.14 op/s 845321.79 op/s 0.10% >> >> Geomean: +3.34% >> >> Experiment environment: Linux 3.19.3, GCC 4.9.3 prerelease, Core-i7 >> 4770, 32G RAM, 10GbE >> >> LMbench microbenchmark also shows reduction in various latencies, as >> well as increase of throughputs. > > Please show multiple run data for all permutations of supported gcc > version/arch ;-) >
He did say optional. So I'd imagine it would be a Kconfig of its own. So the default can be as today, but people that want to experiment need not hack the source code.
Cheers Boaz
> -Mike
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