openssl performance delta built-in vs custom compiled
Dimitri John Ledkov
xnox at ubuntu.com
Sun Dec 21 05:26:47 UTC 2014
On 20 December 2014 at 21:15, Marcus Pollice <marcus.pollice at gmail.com> wrote:
> On 16.12.2014 16:33, Sam Bull wrote:
>> Nevermind, I just realised the performance you're seeing is the other
>> way round. I've no idea why Ubuntu's would be faster, that is strange.
> I'm familiar with Gentoo and several compiler options, but none of these
> things apply here. openssl uses hand-optimized assembly code for some
> algorithms. Since the peak performance for large data size is approximately
> the same, I'd point to other optimizations like memory accesses. But so far
> I've failed to replicate the behavior of the Ubuntu binaries and still hope
> someone knowledgeable chime in.
Note that these days compilers optimise C at times much better than
hand-crafted (crippled) assembly.
Plus if one has compatible CPUs the hardware engines kick in thus
making comparison harder (e.g. AESNI, RDRAND etc.)
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.
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