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From: Linus Torvalds <torvalds@linux-foundation.org>
To: Suresh Siddha <suresh.b.siddha@intel.com>
Cc: Ingo Molnar <mingo@kernel.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>
Subject: Re: [PATCH 2/3] x86: x2apic/cluster: Make use of lowest priority delivery mode
Date: Mon, 21 May 2012 11:18:04 -0700	[thread overview]
Message-ID: <CA+55aFx3ogOzGWZvfETgoKqoLzTc7qw6QjmouSLG4JF9aRdjig@mail.gmail.com> (raw)
In-Reply-To: <1337623623.1997.115.camel@sbsiddha-desk.sc.intel.com>

On Mon, May 21, 2012 at 11:07 AM, Suresh Siddha
<suresh.b.siddha@intel.com> wrote:
>
> All the cluster members of a given x2apic cluster belong to the same
> package. These x2apic cluster id's are setup by the HW and not by the
> SW. And only one cluster (with one or multiple members of that cluster
> set) can be specified in the interrupt destination field of the routing
> table entry.

Ok, then the main question ends up being if there are enough cache or
power domains within a cluster to still worry about it.

For example, you say "package", but that can sometimes mean multiple
dies, or even just split caches that are big enough to matter
(although I can't think of any such right now on the x86 side - Core2
Duo had huge L2's, but they were shared, not split).

> Power aware interrupt routing in IVB does this. And the policy of
> whether you want the interrupt to be routed to the busy core (to save
> power) or an idle core (for minimizing the interruptions on the busy
> core) can be selected by the SW (using IA32_ENERGY_PERF_BIAS MSR).

Sounds like we definitely would want to support this at least in the
IVB timeframe then.

But I do agree with Ingo that it would be really good to actually see
numbers (and no, I don't mean "look here, now the irq's are nicely
spread out", but power and/or performance numbers showing that it
actually helps something).

                   Linus

  reply	other threads:[~2012-05-21 18:18 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 [this message]
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

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