[Bug 236233] Python multiprocessing is 4x slower with 11.2 compared to 11.0 kernel

bugzilla-noreply at freebsd.org bugzilla-noreply at freebsd.org
Wed Mar 6 14:58:44 UTC 2019


https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=236233

--- Comment #6 from Alex Richardson <arichardson at FreeBSD.org> ---
For now setting vm.pmap.pti=0 in /boot/loader.conf brings the testing time back
down to 25.89s. Meltdown mitigation should not be too important for this server
so I will disable it for now.

I guess switching to separate page tables causes a lot of overhead with nested
paging and maybe due to the timing changes there are more syscalls so again
more overhead.

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