On 21.12.2014 06:26, Dimitri John Ledkov wrote:
Note that these days compilers optimise C at times much better than
hand-crafted (crippled) assembly.
I'm aware of this, but it's still not universally true. Also this would
have to go to the upstream developers.
Plus if one has compatible CPUs the hardware engines kick in thus
making comparison harder (e.g. AESNI, RDRAND etc.)
Correct but not applicable, since I compared the performance on the same
machine using the same version, with these features enabled in both
cases. Also since I focused on hash algorithm performance it wouldn't
have changed something.
You are not showing your build log, the chroot used to build and the
package version of a toolchain used.... Note that launchpad.net
publishes full build logs for all binaries including the host kernel
and toolchain packages used. Note that binaries are preserved in
debian/ubuntu and not rebuilt from scratch with each kernel / gcc /
binutils uploads, thus one can have binaries published in a stable
release built with a toolchain that's no longer available in the
archive. Thus you need to compare the toolchain you are using with the
one used to build the corresponding openssl binary package you are
trying to match on a same architecture.
Thanks for pointing me into this direction. From a first glance on the
buildlog I can infer that the same gcc release was used for the package
in 14.04 as I used for compiling. I didn't use a chroot at all, I just
downloaded the tarball, extracted, configured and compiled. It's fairly
easy to replicate this process using a live image. I also didn't use the
Debian/Ubuntu patchset, which is what I will look at more closely now. I
suspect that maybe one of these patches changes something that affects
performance for small data sizes. Is there some documentation available
somewhere which patch changes what specifically?
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