x86_64 is also faster ? Not so fast...
Posted Oct 18, 2008 10:18 UTC (Sat) by khim
In reply to: And they are happy with 32bit Flash too
Parent article: Linux now an equal Flash player (Linux-Watch)
x86_64 is also faster than x86, although not so much as to make it super obvious.
If you actually check the facts you'll find that x86-64 is only faster for fp, for integer calculations results are quite unclear - from 30% gain to 40% (yes, 40%) loss. Average win of 1.6% to 3.8% does not look very compelling.
So there's basically no upside to x86 binaries.
Oh, there are is: huge population of 32bit systems. That's HUGE upside. If you want to support just one binary (and that's significantly easier then to support two) it's huge win. And as there are few downsides...
Each duplicated library is wasted resources, and these can add up to a lot depending upon how many they are (try loading all the gnomelibs for both arches, it's not tiny).
If you compare sizes of all such libraries with 8GB of RAM (and there are no need to use 64bit binaries if you have less - kernel may be, userspace - no)... that's still tiny potatoes. There are significant pressure upon CPU cache, true, but as shown above x86-64 can be problem by itself there, so no clear win from "pure 64-bit system"... "Pure 64-bit system" is more about bragging rights than about real benefits...
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