Date: Fri, 8 Jun 2018 16:40:33 +0200 From: Gary Jennejohn <gljennjohn@gmail.com> To: Andriy Gapon <avg@FreeBSD.org> Cc: FreeBSD Current <freebsd-current@FreeBSD.org> Subject: Re: Is kern.sched.preempt_thresh=0 a sensible default? Message-ID: <20180608164033.5ff948f9@ernst.home> In-Reply-To: <b7c4d137-e582-49d1-fe3f-962a33b561f5@FreeBSD.org> 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> <b7c4d137-e582-49d1-fe3f-962a33b561f5@FreeBSD.org>
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On Fri, 8 Jun 2018 17:18:43 +0300 Andriy Gapon <avg@FreeBSD.org> wrote: > 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. > I hope you will eventually because that's what I use. I find its scheduling of interactive processes much better than ULE. -- Gary Jennejohn
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