Intel C2D COREs not used equally in FreeBSD 7.0-CURRENT i386
youshi10 at u.washington.edu
youshi10 at u.washington.edu
Wed Jun 6 22:45:07 UTC 2007
On Wed, 6 Jun 2007, Doug Ambrisko wrote:
> 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
> on amd64!
>
> 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.
>
> Doug A.
If things are setup properly with 32-/64-bit lib profiling, there should be little issue with things, unless it's dealing with kernel level drivers (i.e. nvidia-drivers, etc).
This should be true not just for nspluginwrapper, but also programs like win32-codecs, and the like, so long as the paths aren't incorrectly hardcoded when linked in the codec (haven't come across that though).
Of course you probably won't see a big performance boost for any 64-bit architectures in the codecs (SSE3, SSE4 for Intel and whatever AMD's using for their specialized FP stuff), but that's true for Windows machines as well.
-Garrett
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