"GHUM" <[EMAIL PROTECTED]> wrote in message news:[EMAIL PROTECTED] |I looked at the virtual machine bytecode of python programs: | | def f(whatever): | text="Hallo"+whatever | return text | | import dis | dis.dis(f) | 2 0 LOAD_CONST 1 ('Hallo') | 3 LOAD_FAST 0 (whatever) | 6 BINARY_ADD | 7 STORE_FAST 1 (text) | | 3 10 LOAD_FAST 1 (text) | 13 RETURN_VALUE | | | and now I am curious: how long does one LOAD_FAST take? I am thinking | of something like back in the assembler-world, where there existed | tables like: | | LDA -> 2 cycles | BNE -> 2 cycles, 3 on branch | | of course, the "real time" is dependand on many factors, esp. the | speed of the processor. | But ... is there a relative scale somewhere? | | Somehting like | | LOAD_CONST 1 arbitraryUnit | LOAD_FAST 1.9 arbitraryUnits | RETURN_VALUE 8.0 arbitraryUnits | | ??? | | my Google queries did not reveal anything usefull so far. Any hints?
There is no such table that I know of and there hardly could be, as the relative times will depend on hardware, OS, C compiler (including optimization settings), as well as the objects on the stack to be operated on. Consider BINARY_ADD. Pretty fast for 2 ints, arbitrarily slow for arbitrary user-class objects. There are a few things knowns, such as _FAST versions being faster that other versions, and that eliminating unneeded codes is faster than not. Developers usually test proposed 'speedup' changes on several platforms. tjr -- http://mail.python.org/mailman/listinfo/python-list
