From: Bart Van Assche <bart.vanassche@sandisk.com>
To: Christoph Hellwig <hch@lst.de>
Cc: "axboe@fb.com" <axboe@fb.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
Keith Busch <keith.busch@intel.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"tglx@linutronix.de" <tglx@linutronix.de>
Subject: Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag
Date: Mon, 20 Jun 2016 15:21:47 +0200 [thread overview]
Message-ID: <066e6b9d-34a8-5917-4ad8-cb466d3389c3@sandisk.com> (raw)
In-Reply-To: <20160620122219.GA29059@lst.de>
On 06/20/2016 02:22 PM, Christoph Hellwig wrote:
> On Thu, Jun 16, 2016 at 05:39:07PM +0200, Bart Van Assche wrote:
>> On 06/16/2016 05:20 PM, Christoph Hellwig wrote:
>>> On Wed, Jun 15, 2016 at 09:36:54PM +0200, Bart Van Assche wrote:
>> My concern
>> is that I doubt that there is an interrupt assignment scheme that works
>> optimally for all workloads. Hence my request to preserve the ability to
>> modify interrupt affinity from user space.
>
> I'd say let's do such an interface incrementally based on the use
> case - especially after we get networking over to use common code
> to distribute the interrupts. If you were doing something like this
> with the current blk-mq code it wouldn't work very well due to the
> fact that you'd have a mismatch between the assigned interrupt and
> the blk-mq queue mapping anyway.
>
> It might be a good idea to start brainstorming how we'd want to handle
> this change - we'd basically need a per-device notification that the
> interrupt mapping changes so that we can rebuild the queue mapping,
> which is somewhat similar to the lib/cpu_rmap.c code used by a few
> networking drivers. This would also help with dealing with cpu
> hotplug events that change the cpu mapping.
A notification mechanism that reports interrupt mapping changes will
definitely help. What would also help is an API that allows drivers to
query the MSI-X IRQ of an adapter that is nearest given a cpumask, e.g.
hctx->cpumask. Another function can then map that IRQ into an index in
the range 0..n-1 where n is the number of MSI-X interrupts for that
adapter. Every blk-mq/scsi-mq driver will need this functionality to
decide which IRQ to associate with a block layer hctx.
Bart.
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WARNING: multiple messages have this Message-ID (diff)
From: Bart Van Assche <bart.vanassche@sandisk.com>
To: Christoph Hellwig <hch@lst.de>
Cc: Keith Busch <keith.busch@intel.com>,
"tglx@linutronix.de" <tglx@linutronix.de>,
"axboe@fb.com" <axboe@fb.com>,
"linux-block@vger.kernel.org" <linux-block@vger.kernel.org>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-nvme@lists.infradead.org" <linux-nvme@lists.infradead.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag
Date: Mon, 20 Jun 2016 15:21:47 +0200 [thread overview]
Message-ID: <066e6b9d-34a8-5917-4ad8-cb466d3389c3@sandisk.com> (raw)
In-Reply-To: <20160620122219.GA29059@lst.de>
On 06/20/2016 02:22 PM, Christoph Hellwig wrote:
> On Thu, Jun 16, 2016 at 05:39:07PM +0200, Bart Van Assche wrote:
>> On 06/16/2016 05:20 PM, Christoph Hellwig wrote:
>>> On Wed, Jun 15, 2016 at 09:36:54PM +0200, Bart Van Assche wrote:
>> My concern
>> is that I doubt that there is an interrupt assignment scheme that works
>> optimally for all workloads. Hence my request to preserve the ability to
>> modify interrupt affinity from user space.
>
> I'd say let's do such an interface incrementally based on the use
> case - especially after we get networking over to use common code
> to distribute the interrupts. If you were doing something like this
> with the current blk-mq code it wouldn't work very well due to the
> fact that you'd have a mismatch between the assigned interrupt and
> the blk-mq queue mapping anyway.
>
> It might be a good idea to start brainstorming how we'd want to handle
> this change - we'd basically need a per-device notification that the
> interrupt mapping changes so that we can rebuild the queue mapping,
> which is somewhat similar to the lib/cpu_rmap.c code used by a few
> networking drivers. This would also help with dealing with cpu
> hotplug events that change the cpu mapping.
A notification mechanism that reports interrupt mapping changes will
definitely help. What would also help is an API that allows drivers to
query the MSI-X IRQ of an adapter that is nearest given a cpumask, e.g.
hctx->cpumask. Another function can then map that IRQ into an index in
the range 0..n-1 where n is the number of MSI-X interrupts for that
adapter. Every blk-mq/scsi-mq driver will need this functionality to
decide which IRQ to associate with a block layer hctx.
Bart.
WARNING: multiple messages have this Message-ID (diff)
From: bart.vanassche@sandisk.com (Bart Van Assche)
Subject: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag
Date: Mon, 20 Jun 2016 15:21:47 +0200 [thread overview]
Message-ID: <066e6b9d-34a8-5917-4ad8-cb466d3389c3@sandisk.com> (raw)
In-Reply-To: <20160620122219.GA29059@lst.de>
On 06/20/2016 02:22 PM, Christoph Hellwig wrote:
> On Thu, Jun 16, 2016@05:39:07PM +0200, Bart Van Assche wrote:
>> On 06/16/2016 05:20 PM, Christoph Hellwig wrote:
>>> On Wed, Jun 15, 2016@09:36:54PM +0200, Bart Van Assche wrote:
>> My concern
>> is that I doubt that there is an interrupt assignment scheme that works
>> optimally for all workloads. Hence my request to preserve the ability to
>> modify interrupt affinity from user space.
>
> I'd say let's do such an interface incrementally based on the use
> case - especially after we get networking over to use common code
> to distribute the interrupts. If you were doing something like this
> with the current blk-mq code it wouldn't work very well due to the
> fact that you'd have a mismatch between the assigned interrupt and
> the blk-mq queue mapping anyway.
>
> It might be a good idea to start brainstorming how we'd want to handle
> this change - we'd basically need a per-device notification that the
> interrupt mapping changes so that we can rebuild the queue mapping,
> which is somewhat similar to the lib/cpu_rmap.c code used by a few
> networking drivers. This would also help with dealing with cpu
> hotplug events that change the cpu mapping.
A notification mechanism that reports interrupt mapping changes will
definitely help. What would also help is an API that allows drivers to
query the MSI-X IRQ of an adapter that is nearest given a cpumask, e.g.
hctx->cpumask. Another function can then map that IRQ into an index in
the range 0..n-1 where n is the number of MSI-X interrupts for that
adapter. Every blk-mq/scsi-mq driver will need this functionality to
decide which IRQ to associate with a block layer hctx.
Bart.
next prev parent reply other threads:[~2016-06-20 13:21 UTC|newest]
Thread overview: 132+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-14 19:58 automatic interrupt affinity for MSI/MSI-X capable devices V2 Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` [PATCH 01/13] irq/msi: Remove unused MSI_FLAG_IDENTITY_MAP Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-16 9:05 ` Bart Van Assche
2016-06-16 9:05 ` Bart Van Assche
2016-06-14 19:58 ` [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-15 8:44 ` Bart Van Assche
2016-06-15 8:44 ` Bart Van Assche
2016-06-15 10:23 ` Christoph Hellwig
2016-06-15 10:23 ` Christoph Hellwig
2016-06-15 10:42 ` Bart Van Assche
2016-06-15 10:42 ` Bart Van Assche
2016-06-15 10:42 ` Bart Van Assche
2016-06-15 15:14 ` Keith Busch
2016-06-15 15:14 ` Keith Busch
2016-06-15 15:28 ` Bart Van Assche
2016-06-15 15:28 ` Bart Van Assche
2016-06-15 16:03 ` Keith Busch
2016-06-15 16:03 ` Keith Busch
2016-06-15 19:36 ` Bart Van Assche
2016-06-15 19:36 ` Bart Van Assche
2016-06-15 20:06 ` Keith Busch
2016-06-15 20:06 ` Keith Busch
2016-06-15 20:12 ` Keith Busch
2016-06-15 20:12 ` Keith Busch
2016-06-15 20:50 ` Bart Van Assche
2016-06-15 20:50 ` Bart Van Assche
2016-06-16 15:19 ` Keith Busch
2016-06-16 15:19 ` Keith Busch
2016-06-22 11:56 ` Alexander Gordeev
2016-06-22 11:56 ` Alexander Gordeev
2016-06-22 11:56 ` Alexander Gordeev
2016-06-16 15:20 ` Christoph Hellwig
2016-06-16 15:20 ` Christoph Hellwig
2016-06-16 15:39 ` Bart Van Assche
2016-06-16 15:39 ` Bart Van Assche
2016-06-20 12:22 ` Christoph Hellwig
2016-06-20 12:22 ` Christoph Hellwig
2016-06-20 12:22 ` Christoph Hellwig
2016-06-20 13:21 ` Bart Van Assche [this message]
2016-06-20 13:21 ` Bart Van Assche
2016-06-20 13:21 ` Bart Van Assche
2016-06-21 14:31 ` Christoph Hellwig
2016-06-21 14:31 ` Christoph Hellwig
2016-06-21 14:31 ` Christoph Hellwig
2016-06-16 9:08 ` Bart Van Assche
2016-06-16 9:08 ` Bart Van Assche
2016-06-14 19:58 ` [PATCH 03/13] irq: Add affinity hint to irq allocation Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` [PATCH 04/13] irq: Use affinity hint in irqdesc allocation Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` [PATCH 05/13] irq/msi: Make use of affinity aware allocations Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 19:58 ` Christoph Hellwig
2016-06-14 21:54 ` Guilherme G. Piccoli
2016-06-14 21:54 ` Guilherme G. Piccoli
2016-06-15 8:35 ` Bart Van Assche
2016-06-15 8:35 ` Bart Van Assche
2016-06-15 8:35 ` Bart Van Assche
2016-06-15 10:10 ` Christoph Hellwig
2016-06-15 10:10 ` Christoph Hellwig
2016-06-15 13:09 ` Guilherme G. Piccoli
2016-06-15 13:09 ` Guilherme G. Piccoli
2016-06-16 15:16 ` Christoph Hellwig
2016-06-16 15:16 ` Christoph Hellwig
2016-06-25 20:05 ` Alexander Gordeev
2016-06-25 20:05 ` Alexander Gordeev
2016-06-30 17:48 ` Christoph Hellwig
2016-06-30 17:48 ` Christoph Hellwig
2016-06-30 17:48 ` Christoph Hellwig
2016-07-01 7:25 ` Alexander Gordeev
2016-07-01 7:25 ` Alexander Gordeev
2016-06-14 19:59 ` [PATCH 07/13] pci: Provide sensible irq vector alloc/free routines Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-23 11:16 ` Alexander Gordeev
2016-06-23 11:16 ` Alexander Gordeev
2016-06-30 16:54 ` Christoph Hellwig
2016-06-30 16:54 ` Christoph Hellwig
2016-06-30 17:28 ` Alexander Gordeev
2016-06-30 17:28 ` Alexander Gordeev
2016-06-30 17:35 ` Christoph Hellwig
2016-06-30 17:35 ` Christoph Hellwig
2016-06-14 19:59 ` [PATCH 08/13] pci: spread interrupt vectors in pci_alloc_irq_vectors Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-25 20:22 ` Alexander Gordeev
2016-06-25 20:22 ` Alexander Gordeev
2016-06-14 19:59 ` [PATCH 09/13] blk-mq: don't redistribute hardware queues on a CPU hotplug event Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` [PATCH 10/13] blk-mq: only allocate a single mq_map per tag_set Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` [PATCH 11/13] blk-mq: allow the driver to pass in an affinity mask Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-07-04 8:15 ` Alexander Gordeev
2016-07-04 8:15 ` Alexander Gordeev
2016-07-04 8:38 ` Christoph Hellwig
2016-07-04 8:38 ` Christoph Hellwig
2016-07-04 9:35 ` Alexander Gordeev
2016-07-04 9:35 ` Alexander Gordeev
2016-07-10 3:41 ` Christoph Hellwig
2016-07-10 3:41 ` Christoph Hellwig
2016-07-12 6:42 ` Alexander Gordeev
2016-07-12 6:42 ` Alexander Gordeev
2016-06-14 19:59 ` [PATCH 12/13] nvme: switch to use pci_alloc_irq_vectors Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` [PATCH 13/13] nvme: remove the post_scan callout Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-14 19:59 ` Christoph Hellwig
2016-06-16 9:45 ` automatic interrupt affinity for MSI/MSI-X capable devices V2 Bart Van Assche
2016-06-16 9:45 ` Bart Van Assche
2016-06-16 9:45 ` Bart Van Assche
2016-06-16 15:22 ` Christoph Hellwig
2016-06-16 15:22 ` Christoph Hellwig
2016-06-26 19:40 ` Alexander Gordeev
2016-06-26 19:40 ` Alexander Gordeev
2016-07-04 8:39 automatic interrupt affinity for MSI/MSI-X capable devices V3 Christoph Hellwig
2016-07-04 8:39 ` [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig
2016-07-04 8:39 ` Christoph Hellwig
2016-07-04 8:39 ` Christoph Hellwig
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