Messages in this thread |  | | From | (David Hinds) | Subject | Re: Pentium memcpy patch. Unintended effect? | Date | 8 Feb 1997 17:21:06 GMT |
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Chad Page (cpage@comp3244.resnet.sjsu.edu) wrote:
: On Fri, 7 Feb 1997 aidas@ixsrs4.ix.netcom.com wrote:
: > : > I patched and compiled 2.1.25 with the Pentium memcpy patch. Everything : > works fine, except for Quake. Now, Quake runs a fair bit choppier. : > : > I'm not really concerned about Quake. I'm more concerned whether this is : > some kind of defect in my hardware, or simply a side effect of the design : > of Quake. The latter seems more likely.
: Quake *heavily* uses the FPU, and from what Ted just said it would : sound like the pentium memcpy patch would affect Quake since the floating : point registers would be swapped every time pentium memcpy is used. This : is also similar to why Carmack won't use MMX instructions in quake :)
Shouldn't the threshold for when the FPU registers will be used for mempcy() be tuneable, then, so that on a system that runs FP-intensive code, the fancy memcpy will only be done when it is faster *including the extra context switch time*?
-- Dave Hinds
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