to all fyi
MMX-IT, STAGE RIGHT
MMX, the graphics-enhanced superset of on-chip instructions that is
supposed to make Intel's P55C Pentium, Klamath Pentium Pro, and other
Pentium-variant chips into Power PC killers, may not be all it's
cracked-up to be, according to a group of x86 programmers close to the
project. In an effort to find out the dope on MMX, your Carapacious
Reporter hooked-up with a former Intel programmer on the MMX project,
who left because he felt the company was simply planning to lie to
customers about the chip's real-world performance.
"Yes, MMX will be faster on some multimedia instructions, once the
software is rewritten for the proper calls. And I suppose that's an
advantage," said Crusty's Intellish friend. "But we should have done
this right from the beginning and architected around the
context-switching problem," he continued.
"What context-switching problem?" your seafood du jour inquired? "The
one that loses us more than 50 clock cycles when software has to
switch from MMX to floating point," Mr. Former Intel Programmer said.
So, what does all of this mean to folks using MMX when it comes out?
"It means that for games, 3D rendering, some multimedia work, and
others that the MMX-enabled version of their software may actually run
slower than the non-MMX version, because of all those save-state
changes from MMX to floating point and back again," he concluded.
Doesn't sound like multimedia nirvana, after all, The Crustacean opined.
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