Date: Wed, 4 Apr 2018 16:08:41 +0200 From: Peter <pmc@citylink.dinoex.sub.org> To: freebsd-stable@FreeBSD.ORG Subject: Re: Try setting kern.sched.preempt_thresh != 0 Message-ID: <pa2ma8$5i0$1@oper.dinoex.de> In-Reply-To: <f3dc3b75-9b2f-ee3e-862b-55414097ad4a@freebsd.org> References: <pa17m7$82t$1@oper.dinoex.de> <9FDC510B-49D0-4722-B695-6CD38CA20D4A@gmail.com> <f3dc3b75-9b2f-ee3e-862b-55414097ad4a@freebsd.org>
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Stefan Esser wrote: > > I'm guessing that the problem is caused by kern.sched.preempt_thresh=0, which > prevents preemption of low priority processes by interactive or I/O bound > processes. > > For a quick test try: > > # sysctl kern.sched.preempt_thresh=1 Hi Stefan, thank You, thats an interesting knob! Only it is actually the other way round: it is not set to 0. My settings (as default) are: kern.sched.steal_thresh: 2 kern.sched.steal_idle: 1 kern.sched.balance_interval: 127 kern.sched.balance: 1 kern.sched.affinity: 1 kern.sched.idlespinthresh: 157 kern.sched.idlespins: 10000 kern.sched.static_boost: 152 kern.sched.preempt_thresh: 80 kern.sched.interact: 30 kern.sched.slice: 12 kern.sched.quantum: 94488 kern.sched.name: ULE kern.sched.preemption: 1 kern.sched.cpusetsize: 4 But then, if I change kern.sched.preempt_thresh to 1 *OR* 0, things behave properly! Precisely, changing from 8 down to 7 changes things completely: >pool alloc free read write read write >cache - - - - - - > ada1s4 7.08G 10.9G 927 0 7.32M 0 > PID USERNAME PRI NICE SIZE RES STATE TIME WCPU COMMAND > 1900 pgsql 82 0 618M 17532K RUN 0:53 34.90% postgres > 1911 admin 81 0 7044K 2824K RUN 6:07 28.34% bash (Notice the PRI values which also look differnt now.) rgds, P.
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