On 2010-Aug-18 04:40:21 +0800, Joerg Schilling <joerg.schill...@fokus.fraunhofer.de> wrote: >Ian Collins <i...@ianshome.com> wrote: >> Some application benefit from the extended register set and function >> call ABI, others suffer due to increased sizes impacting the cache. > >Well, please verify your claims as they do not meet my experience.
I would agree with Ian that it varies. I have recently been evaluating a number of different SHA256 implementations and have just compared the 32-bit vs 64-bit performance on both x86 (P4 nocona using gcc 4.2.1) and SPARC (US-IVa using Studio12). Comparing the different implementations on each platform, the differences between best and worst varied from 10% to 27% depending on the platform (and the slowest algorithm on x86/64 was equal fastest in the other 3 platforms). Comparing the 32-bit vs 64-bit version of each implementation on each platform, the difference between 32-bit and 64-bit varied from -11% to +13% on SPARC and same to +68% on x86. My interpretation of those results is that you can't generalise: The only way to determine whether your application is faster in 32-bit or 64-bit more is to test it. And your choice of algorithm is at least as important as whether it's 32-bit or 64-bit. -- Peter Jeremy
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