Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753150AbYHKNOO (ORCPT ); Mon, 11 Aug 2008 09:14:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751511AbYHKNN7 (ORCPT ); Mon, 11 Aug 2008 09:13:59 -0400 Received: from victor.provo.novell.com ([137.65.250.26]:34449 "EHLO victor.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751498AbYHKNN6 (ORCPT ); Mon, 11 Aug 2008 09:13:58 -0400 Message-ID: <48A03A8D.2050502@novell.com> Date: Mon, 11 Aug 2008 09:11:41 -0400 From: Gregory Haskins User-Agent: Thunderbird 2.0.0.16 (X11/20080720) MIME-Version: 1.0 To: mingo@elte.hu CC: Max Krasnyansky , Peter Zijlstra , dmitry.adamushko@gmail.com, torvalds@linux-foundation.org, pj@sgi.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] cpu hotplug, sched:Introduce cpu_active_map and redoscheddomainmanagment (take 2) References: <1216122229-4865-1-git-send-email-maxk@qualcomm.com> <487DAD86.BA47.005A.0@novell.com> <487E6BD7.3020006@qualcomm.com> <487E7B6C.BA47.005A.0@novell.com> <487EF1E9.2040101@qualcomm.com> <487EFB71.BA47.005A.0@novell.com> <487F9509.9050802@qualcomm.com> <487F6972.BA47.005A.0@novell.com> <1216382024.28405.26.camel@twins> <488052D5.BA47.005A.0@novell.com> <48856BA9.6050609@qualcomm.com> <4885E952.8020708@novell.com> In-Reply-To: <4885E952.8020708@novell.com> X-Enigmail-Version: 0.95.6 OpenPGP: id=D8195319 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="------------enigB425336D945B671D5DE6A128" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5078 Lines: 151 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigB425336D945B671D5DE6A128 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable Hi Ingo, Here is another patch submitted that has not been acked/nacked yet. =20 If you get a free moment, please let me know your thoughts. Here is the = full thread for your convenience: http://lkml.org/lkml/2008/7/22/281 (and FYI it was ACKed by Peter here: http://lkml.org/lkml/2008/7/22/286) -Greg Gregory Haskins wrote: > Max Krasnyansky wrote: >> Greg, correct me if I'm wrong but we seem to have exact same issue=20 >> with the >> rq->rq->online map. Lets take "cpu going down" for example. We're=20 >> clearing >> rq->rd->online bit on DYING event, but nothing AFAICS prevents=20 >> another cpu >> calling rebuild_sched_domains()->partition_sched_domains() in the=20 >> middle of >> the hotplug sequence. >> partition_sched_domains() will happily reset rd->rq->online mask and=20 >> things >> will fail. I'm talking about this path >> >> __build_sched_domains() -> cpu_attach_domain() -> rq_attach_root() >> ... >> cpu_set(rq->cpu, rd->span); >> if (cpu_isset(rq->cpu, cpu_online_map)) >> set_rq_online(rq); >> ... >> >> =20 > > I think you are right, but wouldn't s/online/active above fix that as=20 > well? The active_map didnt exist at the time that code went in=20 > initially ;) > >> --=20 >> >> btw Why didn't we convert sched*.c to use rq->rd->online when it was >> introduced ? ie Instead of using cpu_online_map directly. >> =20 > I think things were converted where they made sense to convert. But=20 > we also had a different goal at that time, so perhaps something was=20 > missed. If you think something else should be converted, please point = > it out. > > In the meantime, I would suggest we consider this patch on top of=20 > yours (applies to tip/sched/devel): > > ---------------------- > > sched: Fully integrate cpus_active_map and root-domain code > Signed-off-by: Gregory Haskins > > diff --git a/kernel/sched.c b/kernel/sched.c > index 62b1b8e..99ba70d 100644 > --- a/kernel/sched.c > +++ b/kernel/sched.c > @@ -6611,7 +6611,7 @@ static void rq_attach_root(struct rq *rq, struct = > root_domain *rd) > rq->rd =3D rd; > > cpu_set(rq->cpu, rd->span); > - if (cpu_isset(rq->cpu, cpu_online_map)) > + if (cpu_isset(rq->cpu, cpu_active_map)) > set_rq_online(rq); > > spin_unlock_irqrestore(&rq->lock, flags); > diff --git a/kernel/sched_fair.c b/kernel/sched_fair.c > index 7f70026..2bae8de 100644 > --- a/kernel/sched_fair.c > +++ b/kernel/sched_fair.c > @@ -1004,7 +1004,7 @@ static void yield_task_fair(struct rq *rq) > * search starts with cpus closest then further out as needed, > * so we always favor a closer, idle cpu. > * Domains may include CPUs that are not usable for migration, > - * hence we need to mask them out (cpu_active_map) > + * hence we need to mask them out (rq->rd->online) > * > * Returns the CPU we should wake onto. > */ > @@ -1032,7 +1032,7 @@ static int wake_idle(int cpu, struct task_struct = > *p) > || ((sd->flags & SD_WAKE_IDLE_FAR) > && !task_hot(p, task_rq(p)->clock, sd))) { > cpus_and(tmp, sd->span, p->cpus_allowed); > - cpus_and(tmp, tmp, cpu_active_map); > + cpus_and(tmp, tmp, task_rq(p)->rd->online); > for_each_cpu_mask(i, tmp) { > if (idle_cpu(i)) { > if (i !=3D task_cpu(p)) { > diff --git a/kernel/sched_rt.c b/kernel/sched_rt.c > index 24621ce..d93169d 100644 > --- a/kernel/sched_rt.c > +++ b/kernel/sched_rt.c > @@ -936,13 +936,6 @@ static int find_lowest_rq(struct task_struct *task= ) > return -1; /* No targets found */ > > /* > - * Only consider CPUs that are usable for migration. > - * I guess we might want to change cpupri_find() to ignore those > - * in the first place. > - */ > - cpus_and(*lowest_mask, *lowest_mask, cpu_active_map); > - > - /* > * At this point we have built a mask of cpus representing the > * lowest priority tasks in the system. Now we want to elect > * the best one based on our affinity and topology. > > -------------- > > Regards, > -Greg > --------------enigB425336D945B671D5DE6A128 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.9 (GNU/Linux) Comment: Using GnuPG with SUSE - http://enigmail.mozdev.org iEYEARECAAYFAkigOo0ACgkQlOSOBdgZUxmY+ACeI9BojR+IKsJYQUnwIP33x6TX b8EAoIxcVfFEhAmb1pztBjNJAf9MN0eX =qdGJ -----END PGP SIGNATURE----- --------------enigB425336D945B671D5DE6A128-- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/