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Because in the profiles I have been doing for these > loads the biggest cost wasn't actually the per-cpu allocation itself but > the cost of zeroing the allocated counter for many CPUs (and then the > counter summarization on exit) and you're not going to get rid of that with > just reshuffling per-cpu fields and adding slab allocator in front. That's a good point ! So skipping the zeroing of per-cpu fields would indeed justify special-casing the single-threaded case. Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com