[Labs-l] [Wikitech-l] Maria DB

Thu Feb 14 16:57:10 UTC 2013

On Feb 14, 2013, at 5:49 PM, Petr Bena <benapetr at gmail.com> wrote:

> I wouldn't be so sure, this apply to non-optimized code, but if you enable optimizations in your compiler together with debug symbols producing, some optimizations may need to be disabled, which may result even in worse performance. <ref> 1 </ref>

No - they're separate. We don't disable optimizization of code. Usually that means some debug symbols are not available because stuff is optimized out - too bad. Debug symbols are still tremendously useful for the rest.

> But I don't really know how much is maria db depending on compiler optimizations so maybe this indeed is not a big problem. But from my own experience replacing debug build with optimized build has a significant performance improvements.
> 
> [1] - http://stackoverflow.com/questions/2880025/why-do-debug-symbols-so-adversely-affect-the-performance-of-threaded-application
> don't be confused by the wrongly asked question - the guy indeed had main problems because of profiling but if you read the table it say:
> 
> Optimized no threading:        0m4.864s
> Optimized threading:           0m2.075s
> 
> Debug no threading (no-pg):    0m10.428s
> Debug threading (no-pg):       0m4.045s
> 
> 
> that means it cause performance issues even when profiling is disabled.

That looks like -O0 vs -O3, which is different from enabling debug symbols or not.

-- 
Mark Bergsma <mark at wikimedia.org>
Lead Operations Architect
Wikimedia Foundation