On 08/04/2011 12:02 PM, Olivier Sallou wrote: > Hi, > we have a package on DebianMed which has performance issue regarding > static build vs dynamic link build (latest gcc) > Has only impacted compile option is the static vs dynamic choice, has > anyone an idea on where we could investigate or how we could speedup this? > > For a simple "-h" call, here is a benchmark: > > # Static build" > osallou@debiansid:/tmp/ncbi-blast-2.2.25+-src/debian/ncbi-blast+/usr/bin$ time > bash -c 'for (( c=1; c<=50; c++ )) ; do ./blastx -h > /dev/null ; done' > > real 0m0.403s > user 0m0.292s > sys 0m0.124s > > # Dynamic build > osallou@debiansid:/tmp/ncbi-blast-2.2.25+-src/debian/ncbi-blast+/usr/bin$ time > bash -c 'for (( c=1; c<=50; c++ )) ; do blastx -h > /dev/null ; done' > > real 0m8.002s > user 0m4.200s > sys 0m3.856s > > Hi, unless the purpose of this program is to display help messages to stdout this is hardly a meaningful benchmark. Starting a dynamic linked library is slower than starting a static one, but that does not yet mean the dynamic version will be so much slower when its running. You might be able to reduce startup time by only linking against the libraries you need or lazyly dynamically loading them. using ld --as-needed is the solution for the former, but see bug 633567 for problems with this. Best Regards, Julian Taylor
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