On Tue, Nov 21, 2017 at 10:03:50AM -0800, Andi Kleen wrote: > > all this is about switching from array to rb_list for the --per-thread case, > > which can be considered as a special use case.. how much do we suffer in > > performance with new code? how about the "perf stat -I 100", would it scale > > ok for extreme cases (many events in -e or -dddd..) > > rbtrees scale by log N, with N being the entries in the tree. > > Even in extreme cases, let's say 10000 events and 1000 cpus it would > need only 8 memory accesses and comparisons for each look up. > Even if we assume cache misses for all of the memory lookups, > at ~200ns per cache miss it's still only 1us per event, which > is negligible. > > In practice not all memory accesses will be misses because > the upper levels of the tree are almost certainly cached > from earlier accesses.
sounds good, thanks jirka
