Merely by accident I noticed that the performance of the
package-installed openssl on recent Ubuntu releases is higher for small
data sizes than a version I build myself from source.
Since the speed difference is biggest at small data sizes and gradually
shrinks until it vanishes almost completely at 8K, I wonder what kind of
optimization causes it.
A similar discrepancy could be observed on other machines, using both
AMD and Intel CPUs. I'd like to understand how to reproduce the
performance figures obtained by the packaged version of openssl.
I already tried different compiler versions (gcc 4.7 and 4.8 for now)
and setting the same compiler flags (the Ubuntu version uses slightly
different settings from the defaults) but none of these things changed
the performance of the version I compiled myself.
Here is a comparison of SHA1 performance of openssl 1.0.1. The first
line is the custom compiled version using the default compiler options
and gcc-4.8. The second line is the packaged version from Ubuntu 14.04.
The tests were conducted using the "openssl speed sha1" commandline.
While these are single-run results, they show the difference quite
obviously. Over a number of runs the numbers would fluctuate a bit, but
the big picture would stay the same.
16 bytes 64 bytes 256 bytes 1024 bytes 8192 bytes
43820.90k 132959.30k 363443.97k 607209.05k 751168.04k
72599.17k 205490.32k 461793.19k 665659.93k 758138.09k
Machine specs:
AMD FX-8350 (4GHz, 8 core, boost enabled)
8GB DDR3-1600
I observed similar performance behavior on different machines across a
variety of AMD and Intel processors and also across a range of different
(older) Ubuntu releases. A similar delta could also be experienced on
the MD5 algorithm. I merely focussed on SHA1 because of work-related
interest.
I'd be grateful if someone could point out the reason for the difference
and also how to compile binaries to achieve the same performance.
Best regards,
--
Marcus Pollice
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