On Sunday 24 January 2016 03:01:57 Kevin Kofler wrote: > Marc Mutz wrote: > > On Friday 22 January 2016 20:46:54 Marc Mutz wrote: > >> Which one is faster? On a dual-core, probably QVector. On a 64-core > >> processor, probably std::vector. > > > > Running attached test program (4 cores + 2-fold HT), I get these numbers: > > That's already 8 virtual cores. He wrote "on a dual-core". :-)
Not that I didn't post the code, so you could run the benchmark on your machine, or with numThreads hard-coded to 2... QVector: 1: 111 2: 100 4: 111 8: 115 16: 139 32: 179 64: 204 128: 337 256: 644 512: 1287 1024: 2611 2048: 5020 4096: 10113 std::vector: 1: 63 2: 63 4: 65 8: 69 16: 119 32: 198 64: 264 128: 375 256: 735 512: 1385 1024: 2719 2048: 5545 4096: 10444 (numThread == 2, same box) Copying is still not significantly slower than ref-counting, even for 4K elements. And yes, this suprises even me, but since it perfectly matches my expecations, at least qualitatively, I won't spend more time trying to understand this. The code is there, I took great care to make it fair, now the CoW fanboys can explain this (or find a bug in the benchmark). At least it seems as if the allocator has a very fast path for alloc/dealloc/alloc/dealloc/etc chains of a same-sized memory block. Thanks, Marc -- Marc Mutz <marc.m...@kdab.com> | Senior Software Engineer KDAB (Deutschland) GmbH & Co.KG, a KDAB Group Company Tel: +49-30-521325470 KDAB - The Qt Experts _______________________________________________ Development mailing list Development@qt-project.org http://lists.qt-project.org/mailman/listinfo/development
