Antoine Pitrou
Tue Dec 11 10:13:31 CET 2012Previous message:
[Python-Dev] More compact dictionaries with faster iteration
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Le Mon, 10 Dec 2012 18:17:57 -0500, Raymond Hettinger <
raymond.hettinger at gmail.com
> a écrit : >> On Dec 10, 2012, at 2:48 AM, Christian Heimes <
> > wrote: >> > On the other hand every lookup and collision checks needs an > > additional multiplication, addition and pointer dereferencing: > > > > entry = entries_baseaddr + sizeof(PyDictKeyEntry) * idx >>> Currently, the dict implementation allows alternative lookup > functions based on whether the keys are all strings. > The choice of lookup function is stored in a function pointer. > That lets each lookup use the currently active lookup > function without having to make any computations or branches. An indirect function call is technically a branch, as seen from the CPU (and not necessarily a very predictable one, although recent Intel CPUs are said to be quite good at that). Regards Antoine.
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