"Raffaello D. Di Napoli" <fasti...@gmail.com> writes: > 2014-08-25 11:25 GMT-04:00 Óscar Fuentes <o...@wanadoo.es>: >> >> On a CPU-intensive application, the 64 bit exe runs 40% slower than >> its 32 bit counterpart. It's a C++ app with a workload typical of a >> compiler. >> >> Are there known slow spots on the 64 bit runtimes? > > You mean, other than the fact that all your pointers (you say > compiler, so you probably use a lot of them in your data structures) > are twice as large and effectively reduce the effective size of your > processor’s data cache?
Yes, there are lots of pointers. The 64 bit executable uses almost 40% more memory than the 32 bit executable. Perhaps it is not all that coincidental that it is slower by the same factor. One important thing I omitted was that I'm using Windows 8.1 64 bits running on VMWare Workstation with Kubuntu 14.04 as host. The same app running on Linux as 64 bits, compiled by gcc 4.8.2, runs twice faster than when running on the Windows VM on 64 bit mode. The performance penalty imposed by VMWare for single-threaded, CPU-bound processes is much lower on my experience. I'll try on a real Windows 64 bit machine as soon as I have access to one, but I'm afraid that the 32bit vs 64bit slowdown is not caused by VMWare. ------------------------------------------------------------------------------ Slashdot TV. Video for Nerds. Stuff that matters. http://tv.slashdot.org/ _______________________________________________ Mingw-w64-public mailing list Mingw-w64-public@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mingw-w64-public
