Date: Tue, 21 Mar 2023 18:52:16 -0400 From: George Mitchell <george+freebsd@m5p.com> To: FreeBSD Hackers <freebsd-hackers@FreeBSD.org> Subject: Periodic rant about SCHED_ULE Message-ID: <a401e51a-250a-64a0-15cb-ff79bcefbf94@m5p.com>
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Yes, you've all heard it before, but I've just reverified on FreeBSD 13.1-RELEASE-p7 that SCHED_ULE gives terrible performance for "make buildworld" in the presence of a totally compute-bound job (misc/dnetc from ports) running at nice 20. World builds in: 15597 seconds with SCHED_4BSD without dnetc 20477 seconds with SCHED_4BSD with dnetc 16006 seconds with SCHED_ULE without dnetc 50290 seconds with SCHED_ULE with dnetc. When I ask why SCHED_ULE is the default scheduler, I have been told more than once that there is some circumstance in which it gives superior performance. But no one seems to know what circumstance that is. Guess what! I propose that SCHED_4BSD be the default scheduler. -- George
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