Re: Proposal to start link time optimisation for Debian Med packages

[Fabian Klötzl <kloetzl@evolbio.mpg.de>]

Hi all,

On 30.03.2016 22:28, Sascha Steinbiss wrote:
>> The promotion of this enhancement I consider to be exceptionally
>> important, especially so if we can tie this up with the continuous
>> integration testing and some benchmarking. For all the folks that wait
>> over some NGS data set to be aligned etc, a 20% reduction of compute
>> time may mean that they see results a working day earlier. 
> 
> Indeed I am really curious about the level of improvement one can get. 
> In GenomeTools we did some experiments compiling the whole code base in
> one big concatenated source file (an 'amalgamation') to allow the compiler
> to optimise, inline etc. as much as possible. I'd consider this an approach 
> with even more optimisation potential than LTO. Looking at the run time of
> demanding tasks (ESA generation, etc) we were IIRC only able to achieve ~10%
> of run time improvement using this level of optimisation. YMMV.
> 

A ~10% speed up is a huge improvement! Especially, as ESA generation is
a task bound by memory accesses. Compilers usually have a hard time
reasoning about those. If LTO or amalgation can help with that, a lot of
bioinformatics applications would benefit from it.

I'll try to come up with some hard numbers for andi and see it they are
anywhere near your 10%.

Best,
Fabian