From: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
To: Afzal Mohammed <afzal.mohd.ma@gmail.com>
Cc: Mike Galbraith <umgwanakikbuti@gmail.com>,
Sasha Levin <levinsasha928@gmail.com>,
Frederic Weisbecker <fweisbec@gmail.com>,
Ingo Molnar <mingo@kernel.org>,
LKML <linux-kernel@vger.kernel.org>,
Chris Metcalf <cmetcalf@ezchip.com>,
"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
Peter Zijlstra <peterz@infradead.org>,
Dave Jones <davej@redhat.com>,
Thomas Gleixner <tglx@linutronix.de>,
Oleg Nesterov <oleg@redhat.com>, Ingo Molnar <mingo@redhat.com>,
Rik van Riel <riel@redhat.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>
Subject: Re: [PATCH 4/4] nohz: Set isolcpus when nohz_full is set
Date: Wed, 20 May 2015 14:00:26 -0700 [thread overview]
Message-ID: <20150520210026.GC6776@linux.vnet.ibm.com> (raw)
In-Reply-To: <20150520203809.GA2940@afzalpc>
On Thu, May 21, 2015 at 02:08:09AM +0530, Afzal Mohammed wrote:
> Hi,
>
> On Sun, May 17, 2015 at 07:30:50AM +0200, Mike Galbraith wrote:
>
> > Yeah, tying nohz_full set to isolcpus set up an initial condition that
> > you have to tear down with cpusets if you want those cpus returned to
> > the general purpose pool. I had considered the kernel setting initial
> > state to be an optimization, but have reconsidered.
>
> > Given that kernel initiated association to isolcpus, a user turning
> > NO_HZ_FULL_ALL on had better not have much generic load to manage. If
>
> On a quad-core desktop system with NO_HZ_FULL_ALL, hackbench took 3x
> time as compared to w/o this patch, except boot cpu every one else
> jobless. Though NO_HZ_FULL_ALL (afaik) is not meant for generic load,
> it was working fine, but not after this - it is now like a single core
> system.
I have to ask... What is your use case? What are you wanting NO_HZ_FULL
to do for you?
Thanx, Paul
> Regards
> Afzal
>
> > he/she does not have CPUSETS enabled, or should Rik's patch rendering
> > isolcpus immutable be merged, he/she would quickly discover that the
> > generic box has been transformed into an utterly inflexible specialist
> > incapable of performing mundane tasks ever again.
>
next prev parent reply other threads:[~2015-05-20 21:00 UTC|newest]
Thread overview: 94+ messages / expand[flat|nested] mbox.gz Atom feed top
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 [this message]
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
-- strict thread matches above, loose matches on Subject: below --
2015-04-24 15:58 [PATCH 0/4] nohz: A few improvements v3 Frederic Weisbecker
2015-04-24 15:58 ` [PATCH 4/4] nohz: Set isolcpus when nohz_full is set Frederic Weisbecker
2015-04-24 20:07 ` Gene Heskett
2015-04-25 23:13 ` Frederic Weisbecker
2015-04-25 23:50 ` Gene Heskett
2015-04-21 12:23 [PATCH 0/4] nohz: A few improvements v2 Frederic Weisbecker
2015-04-21 12:23 ` [PATCH 4/4] nohz: Set isolcpus when nohz_full is set Frederic Weisbecker
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
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
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