Date: Fri, 8 Jun 2018 17:18:43 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: gljennjohn@gmail.com Cc: FreeBSD Current <freebsd-current@FreeBSD.org> Subject: Re: Is kern.sched.preempt_thresh=0 a sensible default? Message-ID: <b7c4d137-e582-49d1-fe3f-962a33b561f5@FreeBSD.org> In-Reply-To: <20180608142719.32104c84@ernst.home> References: <dc8d0285-1916-6581-2b2d-e8320ec3d894@freebsd.org> <CANCZdfoieekesqKa5RmOp=z2vycsVqnVss7ROnO87YTV-qBUzA@mail.gmail.com> <1d188cb0-ebc8-075f-ed51-57641ede1fd6@freebsd.org> <49fa8de4-e164-0642-4e01-a6188992c32e@freebsd.org> <32d6305b-3d57-4d37-ba1b-51631e994520@FreeBSD.org> <93efc3e1-7ac3-fedc-a71e-66c99f8e8c1e@freebsd.org> <9aaec961-e604-303a-52f3-ee24e3a435d0@FreeBSD.org> <bd122dbb-a708-dbc4-838b-3e1784921eff@FreeBSD.org> <20180608142719.32104c84@ernst.home>
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On 08/06/2018 15:27, Gary Jennejohn wrote: > On Thu, 7 Jun 2018 20:14:10 +0300 > Andriy Gapon <avg@FreeBSD.org> wrote: > >> On 03/05/2018 12:41, Andriy Gapon wrote: >>> I think that we need preemption policies that might not be expressible as one or >>> two numbers. A policy could be something like this: >>> - interrupt threads can preempt only threads from "lower" classes: real-time, >>> kernel, timeshare, idle; >>> - interrupt threads cannot preempt other interrupt threads >>> - real-time threads can preempt other real-time threads and threads from "lower" >>> classes: kernel, timeshare, idle >>> - kernel threads can preempt only threads from lower classes: timeshare, idle >>> - interactive timeshare threads can only preempt batch and idle threads >>> - batch threads can only preempt idle threads >> >> >> Here is a sketch of the idea: https://reviews.freebsd.org/D15693 >> > > What about SCHED_4BSD? Or is this just an example and you chose > SCHED_ULE for it? I haven't looked at SCHED_4BSD code at all. -- Andriy Gapon
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