>>>>> Samuel Gaudard writes: Samuel> The choice to compile in 64 bits comes from our customer even though we can Samuel> advise him not to. Our priority on this application is performance and Samuel> stability. I was wondering if using 32 bits binaries under a 64 bit os would Samuel> slow down the execution (as the os deals with 64 bits blocks). If you have Samuel> any idea about that. The performance impact depends on the application. 64 bit applications double the size of some data and data structures, which will slow down the application. If the application requires 64 bit integer computations, a 64 bit "long" or "long long" running in 64 bit mode will be faster than a synthesized 64 bit "long long" running in 32 bit mode. If the application needs to access more data than 32 bit addressing can reference, it is better to map in all of the data as a 64 bit application than to manually swap it into a 32 bit address space. If those issues do not apply, the application should be compiled as 32 bit. I do not understand the comment about 64 bit blocks. 64 bit AIX kernels run 32 bit applications at full speed. David P.S. Please use a different email account to contact the GCC Project instead of sending email with boiler plate legal threats.
