On Feb 9, 2008 2:29 PM, Francesc Altet <[EMAIL PROTECTED]> wrote: > Chuck, > > One more thing on this. I've been doing some benchmarking with my > opt_memcpy() macro in the quicksort_string function, and I should say > that while it is definitely more efficient than my system memcpy for > small values of n (the number of bytes to copy), this doesn't keep true > for all values of n. For example, for n<16, opt_memcpy() can be more > than 4x faster than system memcpy (and this is why I naively thought > that it would be faster in general). However, for n>80, memcpy beats > opt_memcpy between a 25% and 100% (depending on whether n is divisible > by 2, 4 or 8). This is on my Linux system (Ubuntu 7.10), but perhaps > with Windows the behaviour can be different. > > I think I would be able to come up with a routine that can offer a > balance between opt_memcpy and system memcpy, but that should take some > time. So, until I (or anybody else) do more research on this, I think > it would be safer if you use system memcpy for string sorting in NumPy. >
The memcpy in newer compilers is actually pretty good. For integers and such it sometime compiles inline using integer assignments, but I was loath to make it the default implementation until >= 4.1.x gcc became more common. However, strings might be a good place to use it. Chuck
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