20:17 mannerov: looks like mmap is not free
20:17 mannerov: with MAP_POPULATE, which preloads all the memfd file, I get 10 times the time to memset it
20:18 mannerov: if I don't use MAP_POPULATE, the mmap is fast, but the memset is slower (10 times slower that it is else)
20:18 mannerov: so basically accessing the pages of the memfd file is not cheap (when they are not mapped yet)
20:18 mannerov: still it's only 10 times the cost of an optimized access (memset)
20:39 mannerov: the cost is much lower with huge maps
20:40 mannerov: sadly the functionnality is not usable unless the user with root does some configs stuff
20:50 mannerov: so the problem is the same with the normal malloc, so the memfd solution is not slower there (except when it mmaps back when the data is needed ofc)