From: Frederic Weisbecker <fweisbec@gmail.com>
To: Chris Metcalf <cmetcalf@ezchip.com>
Cc: Peter Zijlstra <peterz@infradead.org>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
Ingo Molnar <mingo@redhat.com>,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/2] nohz: make nohz_full imply isolcpus
Date: Thu, 9 Apr 2015 14:45:25 +0200 [thread overview]
Message-ID: <20150409124524.GA17709@lerouge> (raw)
In-Reply-To: <55266A54.30304@ezchip.com>
On Thu, Apr 09, 2015 at 08:02:28AM -0400, Chris Metcalf wrote:
> On 4/9/2015 4:29 AM, Peter Zijlstra wrote:
> >On Wed, Apr 08, 2015 at 02:12:34PM -0400, Chris Metcalf wrote:
> >
> >>>But you're doing the reverse! You're setting nohz_full for isolcpus, not
> >>>limiting the nohz_full mask to isolcpus.
> >>Ah, I see. Yes, that's right.
> >No its not, you should correct me when I'm wrong ;-)
>
> Oh, I have no problem with that :-) But, now that I know what was confusing
> you about the patch I see what it was you were saying with your English
> above too. I thought you were saying something like "making nohz_full
> imply isolcpus" again, but you weren't. Phew, OK, I think we're done
> talking at cross-purposes.
>
> >So the problem is that:
> >
> >+ tick_nohz_full_set_cpus(cpu_isolated_map);
> >
> >reads like you're doing:
> >
> > nohz_full_map |= isolcpus_map
> >
> >But in actual fact you're doing:
> >
> > isolcpus_map |= nohz_full_map
> >
> >So that function is retarded, but the logic is fine.
> >
> >So NAK on both patches for the reason that they're utterly confusing as
> >to wtf they actually do.
>
> What about tick_nohz_full_cpumask_or(cpu_isolated_map) ?
> At that point maybe the similarity to the existing cpumask API will make
> it more clear that we are modifying the argument?
>
> If not, do you have any suggestions what might do better? Obviously
> the goal is to make it something that macroizes away, otherwise I'd
> suggest just explicitly using an #ifdef and cpumask_or().
Possible alternative: do it the other way around.
cpu_isolated_map is allocated and filled early (__setup or sched_init())
before tick_init() and tick_init() is before sched_init_smp() which first uses
cpu_isolated_map(). So we can call some sched_isolated_map_add(struct cpumask *cpumask)
from tick_nohz_init().
next prev parent reply other threads:[~2015-04-09 12:45 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-03 16:24 [PATCH 1/2] nohz: add tick_nohz_full_set_cpus() API cmetcalf
2015-04-03 16:24 ` [PATCH 2/2] nohz: make nohz_full imply isolcpus cmetcalf
2015-04-03 17:42 ` Frederic Weisbecker
2015-04-03 19:20 ` Chris Metcalf
2015-04-04 14:10 ` Rik van Riel
2015-04-04 17:09 ` Chris Metcalf
2015-04-05 5:05 ` Ingo Molnar
2015-04-06 17:15 ` Chris Metcalf
2015-04-06 18:16 ` [PATCH v2 1/2] nohz: add tick_nohz_full_clear_cpus() and _set_cpus() APIs cmetcalf
2015-04-06 18:16 ` [PATCH v2 2/2] nohz: make nohz_full imply isolcpus cmetcalf
2015-04-07 22:29 ` Frederic Weisbecker
2015-04-08 9:41 ` Peter Zijlstra
2015-04-08 14:04 ` Chris Metcalf
2015-04-08 14:26 ` Peter Zijlstra
2015-04-08 15:21 ` Chris Metcalf
2015-04-08 17:24 ` Frederic Weisbecker
2015-04-08 19:20 ` [PATCH v3 1/2] nohz: add tick_nohz_full_clear_cpus() and _set_cpus() APIs cmetcalf
2015-04-08 19:20 ` [PATCH v3 2/2] nohz: set isolcpus when nohz_full is set cmetcalf
2015-04-08 17:27 ` [PATCH v2 2/2] nohz: make nohz_full imply isolcpus Peter Zijlstra
2015-04-08 18:12 ` Chris Metcalf
2015-04-09 8:29 ` Peter Zijlstra
2015-04-09 12:02 ` Chris Metcalf
2015-04-09 12:45 ` Frederic Weisbecker [this message]
2015-04-09 16:59 ` [PATCH v5] nohz: set isolcpus when nohz_full is set Chris Metcalf
2015-04-09 17:12 ` Peter Zijlstra
2015-04-10 1:05 ` Mike Galbraith
2015-04-10 15:33 ` Chris Metcalf
2015-04-10 15:57 ` Mike Galbraith
2015-04-09 17:00 ` [PATCH v4 1/2] nohz: add tick_nohz_full_cpumask_or() and _andnot() APIs Chris Metcalf
2015-04-09 17:00 ` [PATCH v4 2/2] nohz: set isolcpus when nohz_full is set Chris Metcalf
2015-04-09 17:07 ` [PATCH v4 1/2] nohz: add tick_nohz_full_cpumask_or() and _andnot() APIs Peter Zijlstra
2015-04-09 17:24 ` Chris Metcalf
2015-04-09 17:42 ` Peter Zijlstra
2015-04-09 18:01 ` [PATCH v6 1/2] nohz: add tick_nohz_full_add_cpus_to() and _remove_cpus_from() APIs Chris Metcalf
2015-04-09 18:01 ` [PATCH v6 2/2] nohz: set isolcpus when nohz_full is set Chris Metcalf
2015-04-10 1:37 ` Frederic Weisbecker
2015-04-10 20:53 ` [PATCH v7 1/2] nohz: add tick_nohz_full_add_cpus_to() and _remove_cpus_from() APIs Chris Metcalf
2015-04-10 20:53 ` [PATCH v7 2/2] nohz: set isolcpus when nohz_full is set Chris Metcalf
2015-04-14 0:37 ` Frederic Weisbecker
2015-04-14 15:17 ` [PATCH v8 1/2] nohz: add tick_nohz_full_add_cpus_to() API Chris Metcalf
2015-04-14 15:17 ` [PATCH v8 2/2] nohz: set isolcpus when nohz_full is set Chris Metcalf
2015-04-14 15:26 ` Frederic Weisbecker
2015-04-14 16:45 ` Peter Zijlstra
2015-04-14 0:33 ` [PATCH v7 1/2] nohz: add tick_nohz_full_add_cpus_to() and _remove_cpus_from() APIs Frederic Weisbecker
2015-04-14 0:49 ` Chris Metcalf
2015-04-14 15:34 ` Frederic Weisbecker
2015-04-10 1:34 ` [PATCH v6 " Frederic Weisbecker
2015-04-10 15:31 ` Chris Metcalf
2015-04-06 18:29 ` [PATCH v2 1/2] nohz: add tick_nohz_full_clear_cpus() and _set_cpus() APIs Frederic Weisbecker
2015-04-06 19:09 ` Chris Metcalf
2015-04-07 9:33 ` Ingo Molnar
2015-04-03 18:08 ` [PATCH 2/2] nohz: make nohz_full imply isolcpus Mike Galbraith
2015-04-03 19:21 ` Chris Metcalf
2015-04-04 2:03 ` Mike Galbraith
2015-04-04 3:43 ` Mike Galbraith
2015-04-06 19:28 ` Rik van Riel
2015-04-07 3:10 ` Mike Galbraith
2015-05-06 16:04 [GIT PULL] nohz: A few improvements v4 Frederic Weisbecker
2015-05-06 16:04 ` [PATCH 1/4] context_tracking: Protect against recursion Frederic Weisbecker
2015-05-07 9:58 ` Ingo Molnar
2015-05-07 11:53 ` Frederic Weisbecker
2015-05-07 11:31 ` [tip:timers/nohz] " tip-bot for Frederic Weisbecker
2015-05-06 16:04 ` [PATCH 2/4] context_tracking: Inherit TIF_NOHZ through forks instead of context switches Frederic Weisbecker
2015-05-07 11:31 ` [tip:timers/nohz] " tip-bot for Frederic Weisbecker
2015-05-06 16:04 ` [PATCH 3/4] nohz: Add tick_nohz_full_add_cpus_to() API Frederic Weisbecker
2015-05-07 11:31 ` [tip:timers/nohz] " tip-bot for Chris Metcalf
2015-05-06 16:04 ` [PATCH 4/4] nohz: Set isolcpus when nohz_full is set Frederic Weisbecker
2015-05-07 11:32 ` [tip:timers/nohz] " tip-bot for Chris Metcalf
2015-05-16 19:39 ` [PATCH 4/4] " Sasha Levin
2015-05-17 5:30 ` Mike Galbraith
2015-05-18 2:17 ` Rik van Riel
2015-05-18 3:29 ` Mike Galbraith
2015-05-18 14:07 ` Rik van Riel
2015-05-18 14:22 ` Mike Galbraith
2015-05-18 14:52 ` Rik van Riel
2015-05-19 2:30 ` Mike Galbraith
2015-06-12 19:12 ` Rik van Riel
2015-05-20 20:38 ` Afzal Mohammed
2015-05-20 21:00 ` Paul E. McKenney
2015-05-21 12:12 ` Afzal Mohammed
2015-05-21 12:57 ` Paul E. McKenney
2015-05-21 13:06 ` Frederic Weisbecker
2015-05-21 13:27 ` Paul E. McKenney
2015-05-21 13:29 ` Afzal Mohammed
2015-05-21 14:14 ` Paul E. McKenney
2015-05-21 14:46 ` Frederic Weisbecker
2015-05-21 18:59 ` Mike Galbraith
2015-05-22 14:39 ` Frederic Weisbecker
2015-05-22 15:20 ` Mike Galbraith
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