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From: Suresh Siddha <suresh.b.siddha@intel.com>
To: Ingo Molnar <mingo@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	Alexander Gordeev <agordeev@redhat.com>,
	Arjan van de Ven <arjan@infradead.org>,
	linux-kernel@vger.kernel.org, x86@kernel.org,
	Cyrill Gorcunov <gorcunov@openvz.org>,
	Yinghai Lu <yinghai@kernel.org>,
	Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 2/3] x86: x2apic/cluster: Make use of lowest priority delivery mode
Date: Mon, 21 May 2012 12:56:48 -0700	[thread overview]
Message-ID: <1337630208.1997.141.camel@sbsiddha-desk.sc.intel.com> (raw)
In-Reply-To: <20120521191546.GA28819@gmail.com>

On Mon, 2012-05-21 at 21:15 +0200, Ingo Molnar wrote:
> The one negative effect I mentioned, affine wakeups done by the 
> scheduler, could still bite us - this has to be measured and 
> affine wakeups have to be made less prominent if IRQ handlers 
> start jumping around. We definitely don't want tasks to follow 
> round-robin IRQs around.

Actually this (ping-ponging around idle cpu's in a socket) happens
already today, as the affine wakeups use select_idle_sibling() to wake
up the task on an idle sibling (HT or core sibling) if the cpu on which
the task is woken-up is busy with something else.

But I agree, somehow all these need to work together. For example to
save power, what we want is the idle core to stay in idle with least
number of interruptions, with interrupts routed to busy cores, scheduler
not aggressively waking the tasks up on idle cores etc.

One quick thought is to use the cpufreq governor decisions and if all
the cpu's in the package are in lower p-states, then we can default for
power-saving decisions, otherwise if any cpu is at P0, switch for
performance policy(in terms of irq routing, scheduler wake-up decisions
etc) dynamically etc.

thanks,
suresh




      reply	other threads:[~2012-05-21 19:58 UTC|newest]

Thread overview: 69+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-05-18 10:26 [PATCH 2/3] x86: x2apic/cluster: Make use of lowest priority delivery mode Alexander Gordeev
2012-05-18 14:41 ` Cyrill Gorcunov
2012-05-18 15:42   ` Alexander Gordeev
2012-05-18 15:51     ` Cyrill Gorcunov
2012-05-19 10:47       ` Cyrill Gorcunov
2012-05-21  7:11         ` Alexander Gordeev
2012-05-21  9:46           ` Cyrill Gorcunov
2012-05-19 20:53 ` Yinghai Lu
2012-05-21  8:13   ` Alexander Gordeev
2012-05-21 23:02     ` Yinghai Lu
2012-05-21 23:33       ` Yinghai Lu
2012-05-22  9:36         ` Alexander Gordeev
2012-05-21 23:44     ` Suresh Siddha
2012-05-21 23:58       ` [PATCH 1/2] x86, irq: update irq_cfg domain unless the new affinity is a subset of the current domain Suresh Siddha
2012-05-21 23:58         ` [PATCH 2/2] x2apic, cluster: use all the members of one cluster specified in the smp_affinity mask for the interrupt desintation Suresh Siddha
2012-05-22  7:04           ` Ingo Molnar
2012-05-22  7:34             ` Cyrill Gorcunov
2012-05-22 17:21             ` Suresh Siddha
2012-05-22 17:39               ` Cyrill Gorcunov
2012-05-22 17:42                 ` Suresh Siddha
2012-05-22 17:45                   ` Cyrill Gorcunov
2012-05-22 20:03           ` Yinghai Lu
2012-06-06 15:04           ` [tip:x86/apic] x86/x2apic/cluster: Use all the members of one cluster specified in the smp_affinity mask for the interrupt destination tip-bot for Suresh Siddha
2012-06-06 22:21             ` Yinghai Lu
2012-06-06 23:14               ` Suresh Siddha
2012-06-06 15:03         ` [tip:x86/apic] x86/irq: Update irq_cfg domain unless the new affinity is a subset of the current domain tip-bot for Suresh Siddha
2012-08-07 15:31           ` Robert Richter
2012-08-07 15:41             ` do_IRQ: 1.55 No irq handler for vector (irq -1) Borislav Petkov
2012-08-07 16:24               ` Suresh Siddha
2012-08-07 17:28                 ` Robert Richter
2012-08-07 17:47                   ` Suresh Siddha
2012-08-07 17:45                 ` Eric W. Biederman
2012-08-07 20:57                   ` Borislav Petkov
2012-08-07 22:39                     ` Suresh Siddha
2012-08-08  8:58                       ` Robert Richter
2012-08-08 11:04                         ` Borislav Petkov
2012-08-08 19:16                           ` Suresh Siddha
2012-08-14 17:02                             ` [tip:x86/urgent] x86, apic: fix broken legacy interrupts in the logical apic mode tip-bot for Suresh Siddha
2012-06-06 17:20         ` [PATCH 1/2] x86, irq: update irq_cfg domain unless the new affinity is a subset of the current domain Alexander Gordeev
2012-06-06 23:02           ` Suresh Siddha
2012-06-16  0:25           ` Suresh Siddha
2012-06-18  9:17             ` Alexander Gordeev
2012-06-19  0:51               ` Suresh Siddha
2012-06-19 23:43                 ` [PATCH 1/2] x86, apic: optimize cpu traversal in __assign_irq_vector() using domain membership Suresh Siddha
2012-06-19 23:43                   ` [PATCH 2/2] x86, x2apic: limit the vector reservation to the user specified mask Suresh Siddha
2012-06-20  5:56                     ` Yinghai Lu
2012-06-21  9:04                     ` Alexander Gordeev
2012-06-21 21:51                       ` Suresh Siddha
2012-06-20  5:53                   ` [PATCH 1/2] x86, apic: optimize cpu traversal in __assign_irq_vector() using domain membership Yinghai Lu
2012-06-21  8:31                   ` Alexander Gordeev
2012-06-21 21:53                     ` Suresh Siddha
2012-06-20  0:18               ` [PATCH 1/2] x86, irq: update irq_cfg domain unless the new affinity is a subset of the current domain Suresh Siddha
2012-06-21 11:00                 ` Alexander Gordeev
2012-06-21 21:58                   ` Suresh Siddha
2012-05-22 10:12       ` [PATCH 2/3] x86: x2apic/cluster: Make use of lowest priority delivery mode Alexander Gordeev
2012-05-21  8:22 ` Ingo Molnar
2012-05-21  9:36   ` Alexander Gordeev
2012-05-21 12:40     ` Ingo Molnar
2012-05-21 14:48       ` Alexander Gordeev
2012-05-21 14:59         ` Ingo Molnar
2012-05-21 15:22           ` Alexander Gordeev
2012-05-21 15:34           ` Cyrill Gorcunov
2012-05-21 15:36           ` Linus Torvalds
2012-05-21 18:07             ` Suresh Siddha
2012-05-21 18:18               ` Linus Torvalds
2012-05-21 18:37                 ` Suresh Siddha
2012-05-21 19:30                   ` Ingo Molnar
2012-05-21 19:15             ` Ingo Molnar
2012-05-21 19:56               ` Suresh Siddha [this message]

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