On 12/11/06, Steinar H. Gunderson <sgunderson@xxxxxxxxxxx> wrote:
On Mon, Dec 11, 2006 at 11:09:13AM -0200, Daniel van Ham Colchete wrote: >> You know what? I don't. > So test it yourself. You're making the claims, you're supposed to be proving them... > As I said, it is an example. Take floatpoint divisions. You have > plenty of ways of doing it: 387, MMX, SSE, 3dNow, etc... Here GCC have > to make a choice. No, you don't. MMX, SSE and 3Dnow! will all give you the wrong result (reduced precision). SSE2, on the other hand, has double precision floats, so you might have a choice there -- except that PostgreSQL doesn't really do a lot of floating-point anyhow. > And this is only one case. Usually, compiler optimizations are really > complex and the processor's timings counts a lot. You keep asserting this, with no good backing. > If you still can't imagine any case, you can read Intel's assembler > reference. You'll see that there are a lot of ways of doing a lot of > things. I've been programming x86 assembler for ten years or so...
So, I'm a newbie to you. I learned x86 assembler last year.
> Steinar, you should really test it. I won't read the PostgreSQL source > to point you were it could use SSE or SSE2 or whatever. And I won't > read glibc's code. Then you should stop making these sort of wild claims. > You don't need to belive in what I'm saying. You can read GCC docs, > Intel's assembler reference, AMD's docs about their processor and > about how diferent that arch is. I have. /* Steinar */
Okay, I'll do the benchmarks. Just sent an e-mail about this to the list. If you have any sugestions of how to make the benchmark please let-me know. I like when I prove myself wrong. Although it's much better when I'm right :-)... Best regards, Daniel Colchete