Am 21.07.2015 16:33 schrieb "Michael Van Canneyt" <mich...@freepascal.org>: > > > > On Tue, 21 Jul 2015, Sven Barth wrote: > > >> Am 21.07.2015 12:13 schrieb "Michael Van Canneyt" <mich...@freepascal.org >: >>> >>> >>> >>> >>> On Mon, 20 Jul 2015, Serguei TARASSOV wrote: >>> >>>> Hi all, >>>> >>>> I did a small test to compare performance of TFPGMap and TFPHashList in >> >> sequential and random accessing values by keys. >>>> >>>> http://arbinada.com/main/en/node/1511 >>>> >>>> The results are not the same than expected. >>>> In theory, the hash map should give O(1) and O(log2 N) for the sorted >> >> map. >>>> >>>> >>>> Any explanations and suggestions are welcome. >>> >>> >>> >>> In my opinion there is a simple explanation: >>> >>> As a general solution, using generics will always be slower than 'native' >> >> classes. >>> >>> The reason is that any generic implementation which does not place >> >> restrictions on the types used, >>> >>> will be forced to use CompareMem() and Move() for its implementation (as >> >> do the classes in fgl). Even when the generic class is otherwise optimally >> programmed, calling these routines will always be slower than a direct >> comparision in 2 CPU registers in case of integers/pointers. >> >> You are wrong with your assumptions regarding TFPGList: it does not use >> Move(). The base implementation in TFPSList does, but the generic class >> overrides that with an assignment. Otherwise for example Strings wouldn't >> work with TFPGList. > > > I am glad it is not as bad as I thought :) >
I had the same feeling as you when I looked at the code the first time, but then I found out how it is really intended ^^ Regards, Sven
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