From owner-svn-src-head@freebsd.org Thu Feb 16 20:37:56 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 19803CE252E; Thu, 16 Feb 2017 20:37:56 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: from mail-it0-x229.google.com (mail-it0-x229.google.com [IPv6:2607:f8b0:4001:c0b::229]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id DF01111F5; Thu, 16 Feb 2017 20:37:55 +0000 (UTC) (envelope-from rysto32@gmail.com) Received: by mail-it0-x229.google.com with SMTP id k200so7862938itb.1; Thu, 16 Feb 2017 12:37:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc; bh=rClRCAGiIUrezIfdgyP0Eg4lOgJ5EabacG7udbHGe4M=; b=oINLbJpcEdX+7UvKT2gIjwbuxj9lyUjc3vqdYmqu57ox9urEASwXYcg4qU5wlf+P/6 rsbYKqBe8woCdsesH7l4feyFYoFpL/iRaHimy4rJ7o1HnP4hH/ZdqNr1JVMceKXAzOUw 2iV1KedstsrYanhmegICEdjfOZ3Tqri02UuZiNHw27EbgTlkVgYfGxkLkucTa+QVzY8r JFkWVJ+mGBQ2wCZZO/CV0F7w596MxLsVs2prq/VqbmrBxC7iO329oy7sUanTE32UtpzV 3psGsweuame76xr6nHW+sAY6D244KM0EbM2b1IOIcCAyKcJYBBiBt5f5QD3Q5YepD8Kf M4cw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:in-reply-to:references:from:date :message-id:subject:to:cc; bh=rClRCAGiIUrezIfdgyP0Eg4lOgJ5EabacG7udbHGe4M=; b=LGvCI98fvYoqy9FypfycUV5zU4O4uTK3CZG/yWFrgvr4rYfaIVQ6ZKLWXASF3oE04l z41eGHTqmC6l+RJrCIkw8igAzVr1aGnuTbkwnvPm1AAV6JZKcWKewXm1Ji+MX5YUk0dp pjgg1cI5+9S0vhAB3BQ7BOFjGOo12acaUY7kZaw2puBX8E322aL0ZlvyC7J6DsDS+zQ+ B5yCUHHbexl0z8+BoaMP8y5LVd0uncqlmFOtuEtrUQqku4JfZ4s9/wTJIuKHmAmAZ3RV 5jM6F4YgicHOM2N6R4lz5VKWaE56sZZ33MovwAHNxJE9rcQPoRtfWx+zZo7/DBuB3NKT Ajmg== X-Gm-Message-State: AMke39l9oqJkHxX6OhDarSGn13kchAvwcYs2vM2GmqHfxr0Zjv+3pCYHqP8kPBsQFilseMVq/DbeNhif2hVEfg== X-Received: by 10.107.26.205 with SMTP id a196mr3993564ioa.214.1487277475231; Thu, 16 Feb 2017 12:37:55 -0800 (PST) MIME-Version: 1.0 Received: by 10.107.190.71 with HTTP; Thu, 16 Feb 2017 12:37:54 -0800 (PST) In-Reply-To: <201702162031.v1GKVmjA097376@slippy.cwsent.com> References: <201702161941.v1GJfDoP087457@repo.freebsd.org> <201702162031.v1GKVmjA097376@slippy.cwsent.com> From: Ryan Stone Date: Thu, 16 Feb 2017 15:37:54 -0500 Message-ID: Subject: Re: svn commit: r313814 - head/sys/kern To: Cy Schubert Cc: Ryan Stone , "src-committers@freebsd.org" , "svn-src-all@freebsd.org" , "svn-src-head@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.23 X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 16 Feb 2017 20:37:56 -0000 Sorry about that. It's fixed in r313816. On Thu, Feb 16, 2017 at 3:31 PM, Cy Schubert wrote: > In message <201702161941.v1GJfDoP087457@repo.freebsd.org>, Ryan Stone > writes: > > Author: rstone > > Date: Thu Feb 16 19:41:13 2017 > > New Revision: 313814 > > URL: https://svnweb.freebsd.org/changeset/base/313814 > > > > Log: > > Check for preemption after lowering a thread's priority > > > > When a high-priority thread is waiting for a mutex held by a > > low-priority thread, it temporarily lends its priority to the > > low-priority thread to prevent priority inversion. When the mutex > > is released, the lent priority is revoked and the low-priority > > thread goes back to its original priority. > > > > When the priority of that thread is lowered (through a call to > > sched_priority()), the schedule was not checking whether > > there is now a high-priority thread in the run queue. This can > > cause threads with real-time priority to be starved in the run > > queue while the low-priority thread finishes its quantum. > > > > Fix this by explicitly checking whether preemption is necessary > > when a thread's priority is lowered. > > > > Sponsored by: Dell EMC Isilon > > Obtained from: Sandvine Inc > > Differential Revision: https://reviews.freebsd.org/D9518 > > Reviewed by: Jeff Roberson (ule) > > MFC after: 1 month > > > > Modified: > > head/sys/kern/sched_4bsd.c > > head/sys/kern/sched_ule.c > > > > Modified: head/sys/kern/sched_4bsd.c > > ============================================================ > ================= > > = > > --- head/sys/kern/sched_4bsd.c Thu Feb 16 19:00:09 2017 > (r31381 > > 3) > > +++ head/sys/kern/sched_4bsd.c Thu Feb 16 19:41:13 2017 > (r31381 > > 4) > > @@ -816,7 +816,12 @@ sched_class(struct thread *td, int class > > static void > > sched_priority(struct thread *td, u_char prio) > > { > > - > > + struct thread *newtd; > > + struct runq *rq; > > + u_char orig_pri; > > +#ifdef SMP > > + struct thread *cputd; > > +#endif > > > > KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority > change", > > "prio:%d", td->td_priority, "new prio:%d", prio, > KTR_ATTR_LINKED, > > @@ -832,10 +837,43 @@ sched_priority(struct thread *td, u_char > > THREAD_LOCK_ASSERT(td, MA_OWNED); > > if (td->td_priority == prio) > > return; > > + orig_pri = td->td_priority; > > td->td_priority = prio; > > if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) { > > sched_rem(td); > > sched_add(td, SRQ_BORING); > > + } else if (orig_pri < prio && TD_IS_RUNNING(td)) { > > + /* > > + * If we have decreased the priority of a running thread, > we > > + * have to check if it should be preempted. > > + */ > > + rq = &runq; > > + newtd = runq_choose(&runq); > > +#ifdef SMP > > + cputd = runq_choose(&runq_pcpu[td->td_oncpu]); > > + if (newtd == NULL || > > + (cputd != NULL && cputd->td_priority < > td->td_priority)) > > + newtd = cputd; > > +#endif > > + > > + if (newtd != NULL && newtd->td_priority < prio > > +#ifndef FULL_PREEMPTION > > + && (newtd->td_priority <= PRI_MAX_ITHD || > > + prio >= PRI_MIN_IDLE)) > > +#endif > > + ) { > > + if (td == curthread) > > + /* > > + * Don't reschedule the thread here as it > may > > + * be losing priority because it has > released a > > + * mutex, and in that case we need it to > finish > > + * releasing the lock before it gets > preempted. > > + */ > > + td->td_owepreempt = 1; > > + else > > + kick_other_cpu(newtd->td_priority, > > + td->td_oncpu); > > + } > > } > > } > > > > > > Modified: head/sys/kern/sched_ule.c > > ============================================================ > ================= > > = > > --- head/sys/kern/sched_ule.c Thu Feb 16 19:00:09 2017 (r313813) > > +++ head/sys/kern/sched_ule.c Thu Feb 16 19:41:13 2017 (r313814) > > @@ -319,7 +319,7 @@ static void tdq_add(struct tdq *, struct > > #ifdef SMP > > static int tdq_move(struct tdq *, struct tdq *); > > static int tdq_idled(struct tdq *); > > -static void tdq_notify(struct tdq *, struct thread *); > > +static void tdq_notify(struct tdq *, int); > > static struct thread *tdq_steal(struct tdq *, int); > > static struct thread *runq_steal(struct runq *, int); > > static int sched_pickcpu(struct thread *, int); > > @@ -1040,16 +1040,14 @@ tdq_idled(struct tdq *tdq) > > * Notify a remote cpu of new work. Sends an IPI if criteria are met. > > */ > > static void > > -tdq_notify(struct tdq *tdq, struct thread *td) > > +tdq_notify(struct tdq *tdq, int pri) > > { > > struct thread *ctd; > > - int pri; > > int cpu; > > > > if (tdq->tdq_ipipending) > > return; > > - cpu = td_get_sched(td)->ts_cpu; > > - pri = td->td_priority; > > + cpu = TD_ID(tdq); > > Just my luck. The day I svn up and rebuild. > > --- sched_ule.o --- > /opt/src/svn-current/sys/kern/sched_ule.c:1050:8: error: implicit > declaration of function 'TD_ID' is invalid in C99 > [-Werror,-Wimplicit-functi > on-declaration] > cpu = TD_ID(tdq); > ^ > -- > Cheers, > Cy Schubert > FreeBSD UNIX: Web: http://www.FreeBSD.org > > The need of the many outweighs the greed of the few. > > > > ctd = pcpu_find(cpu)->pc_curthread; > > if (!sched_shouldpreempt(pri, ctd->td_priority, 1)) > > return; > > @@ -1675,6 +1673,22 @@ sched_pctcpu_update(struct td_sched *ts, > > ts->ts_ltick = t; > > } > > > > +static void > > +sched_check_preempt(struct tdq *tdq, struct thread *td) > > +{ > > + > > + KASSERT(TD_IS_RUNNING(td), ("thread is not running")); > > + TDQ_LOCK_ASSERT(tdq, MA_OWNED); > > + KASSERT(tdq == TDQ_CPU(td->td_sched->ts_cpu), > > + ("tdq does not contain td")); > > + > > + if (tdq == TDQ_SELF()) { > > + if (sched_shouldpreempt(tdq->tdq_lowpri, td->td_priority, > 0)) > > + td->td_owepreempt = 1; > > + } else > > + tdq_notify(tdq, tdq->tdq_lowpri); > > +} > > + > > /* > > * Adjust the priority of a thread. Move it to the appropriate > run-queue > > * if necessary. This is the back-end for several priority related > > @@ -1726,6 +1740,9 @@ sched_thread_priority(struct thread *td, > > tdq->tdq_lowpri = prio; > > else if (tdq->tdq_lowpri == oldpri) > > tdq_setlowpri(tdq, td); > > + > > + if (oldpri < prio) > > + sched_check_preempt(tdq, td); > > return; > > } > > td->td_priority = prio; > > @@ -1854,7 +1871,7 @@ sched_switch_migrate(struct tdq *tdq, st > > */ > > tdq_lock_pair(tdn, tdq); > > tdq_add(tdn, td, flags); > > - tdq_notify(tdn, td); > > + tdq_notify(tdn, td->td_priority); > > TDQ_UNLOCK(tdn); > > spinlock_exit(); > > #endif > > @@ -2429,7 +2446,7 @@ sched_add(struct thread *td, int flags) > > tdq = sched_setcpu(td, cpu, flags); > > tdq_add(tdq, td, flags); > > if (cpu != PCPU_GET(cpuid)) { > > - tdq_notify(tdq, td); > > + tdq_notify(tdq, td->td_priority); > > return; > > } > > #else > > > > > > >