Date: Thu, 7 Jun 2018 20:14:10 +0300 From: Andriy Gapon <avg@FreeBSD.org> To: FreeBSD Current <freebsd-current@freebsd.org> Cc: Stefan Esser <se@freebsd.org>, "M. Warner Losh" <imp@freebsd.org> Subject: Re: Is kern.sched.preempt_thresh=0 a sensible default? Message-ID: <bd122dbb-a708-dbc4-838b-3e1784921eff@FreeBSD.org> In-Reply-To: <9aaec961-e604-303a-52f3-ee24e3a435d0@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>
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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 -- Andriy Gapon
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