Intel C2D COREs not used equally in FreeBSD 7.0-CURRENT i386
ambrisko at ambrisko.com
Wed Jun 6 16:41:48 UTC 2007
Dag-Erling Sm\xc3\xb8rgrav writes:
| Oliver Fromme <olli at lurza.secnetix.de> writes:
| > It's a common mistake to assume that amd64 only makes sense
| > if you have >= 4GB RAM. There are several reasons why it
| > might be useful to switch from i386 to amd64:
| > - Most programs (though not all) will run faster, because
| > in amd64 mode there are twice as many general-purpose
| > registers, giving compilers much better opportunities
| > for optimizations and caching of values, and reducing
| > slow memory accesses.
| "twice as many" is an understatement. AMD64 has 16 GPRs vs i386's 8 if
| you consider BP, SI, DI and SP as GPRs (as the AMD and Intel literature
| does); in practical terms the score is 12 to 4.
| > - Some applications might benefit from a larger virtual
| > address space > 4 GB. (Note that this is not related
| > to the amount of physical RAM!)
| For instance, Varnish maps its entire storage into memory, and will
| benefit greatly from the increased address space.
| > In practice there's (almost) only one reason not to run
| > FreeBSD/amd64 on amd64-capable hardware: If you depend
| > on a certain piece of software which is known not to run
| > correctly in 64bit mode. Fortunately those are not many.
| The only one I can think of (for a desktop) is the Flash plugin.
Why? With the nspluginwrapper we can running Linux Flash in a FreeBSD
native browser on amd64 or i386. With the appropriate compile foo
or probably by getting a Linux compiled version it would work with
a Linux browser. Nspluginwrapper is great for running i386 plugins
The only thing that is preventing me from running full time on an
amd64 kernel is the kernel support for suspend & resume. I had to
add a small hack the kernel to let the i386 Xserver to run on amd64.
I need to do some more digging to answer some questions that alc had.
Personally, I want to run amd64 full time so I can run and build amd64
and i386 things on my laptop without rebooting at native speed.
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