Hi, 64-big gives you a larger address space. The downside of this is that pointers and longs go from 32-bits to 64-bits. This results in a slight drop in performance.
So in general you should probably expect a 64-bit application to run slightly slower than the same application compiled 32-bit. On x86, the situation is slightly different. x64 gives you more registers and an improved calling convention. This means that the application runs faster, so long as these performance gains are not lost by the increase in memory footprint (from the pointers and longs increasing in size). If you're interested in seeing where the time is going in your application, I'd suggest trying the Performance Analyzer in Sun Studio. Darryl. Elad Lahav wrote: > I wrote a simple benchmark that takes a 1 GB file and encrypts it in parallel > using > libgcrypt. On an 8-core T1000, using 32 threads, the benchmark completed in > ~45 seconds > (after warming the file cache, of course). > I then recompiled everything (libgcrypt and the application) in 64 bits, and > was surprised > to notice no improvement. While I realise that the main purpose of 64 bit > systems is to > increase the amount of addressable memory, I thought that, on a > number-crunching > application such as this benchmark, there would be an advantage to using > bigger integers > that fit into the actual size of the registers. Is there any validity to this > assumption? > > System information: > > uname -a: > SunOS foxtrot 5.11 snv_104 sun4v sparc SUNW,Sun-Fire-T1000 > > cc -V: > cc: Sun C 5.9 SunOS_sparc 2007/05/03 > > Thanks, > --Elad > > P.S., > cpustat/cputrack do not work for me in this release. It worked with Solaris > 10. Is this a > known issue? > _______________________________________________ > perf-discuss mailing list > perf-discuss@opensolaris.org -- Darryl Gove Compiler Performance Engineering Blog: http://blogs.sun.com/d/ Book: http://www.sun.com/books/catalog/solaris_app_programming.xml _______________________________________________ perf-discuss mailing list perf-discuss@opensolaris.org
