> > On 2014/11/04 21:34, jose isaias cabrera wrote: >> Greetings! >> >> I have an application that is written for x32 machines. However, we now >> have a few machines that are x64 and all is well when we are using the >> precompiled x32 DLLs provided by http://www.sqlite.org/download.html. >> Changing the x32 DLLs to x64 DLLs, will it show any difference in speed >> on the x64 machines? Thanks. > > Yeah, might even be slower, but so negligibly that you won't notice. > > Important to note (which many people seem to miss) is that the step up > from 32 to 64 bit computing is an increase in computing > accuracy and capacity, not in speed, though computations on historic 64 > bit variables (which used to be split up into two or more > values to work) might be faster, but they generally make up less than 1% > of the computations in any sane software system (though > exceptions do exist) and so the speed increase is usually miniscule. On > the downside, a 64-bit system uses 64 bit values for all > registers even where 32-bit values could have sufficed, and so all > internal looping through bits or register shifts take longer, but > generally by negligible amounts. (All modern processors are 64 bit anyway > - 32 bit OSes still exist for legacy reasons only). > > It isn't a magic boost - The best way to think of the 64 bit upgrade in > normal programming is: "Able to do larger accuracy > calculations at more or less the same speed".
However, the switch from i386 to x86_64 isn't *just* a switch from 32-bit to 64-bit like ppc32/ppc64 is. It *also* gives you a bunch more registers, which certainly can make things significantly faster. If you are looking at precompiled binaries then compatibility issues also might be relevant. Code built for i386 might literally be compatible with the 80386, using *no* new instructions added since then. Even if it doesn't go that far but only supports i586, that still precludes some important instructions like cmov. Code built for x86_64, on the other hand, will have a 'lowest common denominator' CPU feature set which is distinctly more modern. And which even includes SSE2. So it might be faster for that reason too. -- dwmw2 _______________________________________________ sqlite-users mailing list [email protected] http://sqlite.org:8080/cgi-bin/mailman/listinfo/sqlite-users
