Originally posted by Viper_Scull
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The "Dirndl" On AMD Opterons Are Impressive
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Originally posted by clavko View PostThey already released some of their code under BSD licence,
It would be nice if this code dump would be BSD too.
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Verry impressive results. But those results do remind me of the "compiler deathmatch" use the search function to find it. In that deathmatch gcc could be made A LOT faster than the stock settings. Archlinux four example it's using roughly the stock compiler settings. If this new compiler is just by default having all those optimizing things turned on than the current phoronix comparisons aren't even fair..
Just my 5 cents..
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Originally posted by markg85 View PostVerry impressive results. But those results do remind me of the "compiler deathmatch" use the search function to find it. In that deathmatch gcc could be made A LOT faster than the stock settings. Archlinux four example it's using roughly the stock compiler settings. If this new compiler is just by default having all those optimizing things turned on than the current phoronix comparisons aren't even fair..
Just my 5 cents..
Aggressive optimisations should be used per-package, when you know that they won't break a particular package.
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Originally posted by pingufunkybeat View PostGentoo guys will mostly tell you to stick to -march-native -O2 -pipe, anything more aggressive leads to breakage somewhere.
Aggressive optimisations should be used per-package, when you know that they won't break a particular package.
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Originally posted by pingufunkybeat View PostGentoo guys will mostly tell you to stick to -march-native -O2 -pipe, anything more aggressive leads to breakage somewhere.
Aggressive optimisations should be used per-package, when you know that they won't break a particular package.
I've been playing with -O3 and -Ofast using GCC 4.6
-Ofast has problems with SQlite and wine won't start programs with -O3
I think I may switch back to my tried and tested -Os though
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Originally posted by curaga View PostAny compiler guys around to tell whether a 2-3x increase like this over latest gcc is considered possible/doable? I was under the impression it's already very good, with icc only gaining 10-30% and visual studio less.
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Originally posted by FireBurn View PostThat's -march=native
I've been playing with -O3 and -Ofast using GCC 4.6
-Ofast has problems with SQlite and wine won't start programs with -O3
I think I may switch back to my tried and tested -Os though
As for -Os, it prefers code size over code speed, so unless you are starved for ram I would suggest using -O2 where -O3 causes problems rather than -Os.
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Originally posted by deanjo View PostIn some cases it also leads to slower performance.
Obviously this is due to how complex it is to make correct heuristics regarding those more advanced optimizations. This can be rectified by using PGO (profile-guided optimization) where the compiler gathers all necessary runtime data during an initial run which is then used to correctly determine when and when not to use certain optimizations in order to maximize performance.
When using PGO I've never encountered a situation where -O3 hasn't beaten -O2, the downside of course is that compilation becomes more complex since you need to perform a information gathering execution of the code in between two compiles.
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