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From: Christoph Hellwig <hch@lst.de>
To: "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com>
Cc: Christoph Hellwig <hch@lst.de>,
	tglx@linutronix.de, axboe@fb.com, linux-block@vger.kernel.org,
	linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-nvme@lists.infradead.org
Subject: Re: [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors
Date: Wed, 15 Jun 2016 12:10:45 +0200	[thread overview]
Message-ID: <20160615101045.GB16425@lst.de> (raw)
In-Reply-To: <57607D0E.1060907@linux.vnet.ibm.com>

On Tue, Jun 14, 2016 at 06:54:22PM -0300, Guilherme G. Piccoli wrote:
> On 06/14/2016 04:58 PM, Christoph Hellwig wrote:
>> This is lifted from the blk-mq code and adopted to use the affinity mask
>> concept just intruced in the irq handling code.
>
> Very nice patch Christoph, thanks. There's a little typo above, on 
> "intruced".

fixed.

> Another little typo above in "assining".

fixed a swell.

> I take this opportunity to ask you something, since I'm working in a 
> related code in a specific driver

Which driver?  One of the points here is to get this sort of code out
of drivers and into common code..

> - sorry in advance if my question is 
> silly or if I misunderstood your code.
>
> The function irq_create_affinity_mask() below deals with the case in which 
> we have nr_vecs < num_online_cpus(); in this case, wouldn't be a good idea 
> to trying distribute the vecs among cores?
>
> Example: if we have 128 online cpus, 8 per core (meaning 16 cores) and 64 
> vecs, I guess would be ideal to distribute 4 vecs _per core_, leaving 4 
> CPUs in each core without vecs.

There have been some reports about the blk-mq IRQ distribution being
suboptimal, but no one sent patches so far.  This patch just moves the
existing algorithm into the core code to be better bisectable.

I think an algorithm that takes cores into account instead of just SMT
sibling would be very useful.  So if you have a case where this helps
for you an incremental patch (or even one against the current blk-mq
code for now) would be appreciated.

  parent reply	other threads:[~2016-06-15 10:10 UTC|newest]

Thread overview: 55+ 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 ` [PATCH 01/13] irq/msi: Remove unused MSI_FLAG_IDENTITY_MAP Christoph Hellwig
2016-06-16  9:05   ` Bart Van Assche
2016-06-14 19:58 ` [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig
2016-06-15  8:44   ` Bart Van Assche
2016-06-15 10:23     ` Christoph Hellwig
2016-06-15 10:42       ` Bart Van Assche
2016-06-15 15:14         ` Keith Busch
2016-06-15 15:28           ` Bart Van Assche
2016-06-15 16:03             ` Keith Busch
2016-06-15 19:36               ` Bart Van Assche
2016-06-15 20:06                 ` Keith Busch
2016-06-15 20:12                   ` Keith Busch
2016-06-15 20:50                     ` Bart Van Assche
2016-06-16 15:19                       ` Keith Busch
2016-06-22 11:56                         ` Alexander Gordeev
2016-06-16 15:20                 ` Christoph Hellwig
2016-06-16 15:39                   ` Bart Van Assche
2016-06-20 12:22                     ` Christoph Hellwig
2016-06-20 13:21                       ` Bart Van Assche
2016-06-21 14:31                         ` Christoph Hellwig
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 ` [PATCH 04/13] irq: Use affinity hint in irqdesc allocation 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 ` [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors Christoph Hellwig
2016-06-14 21:54   ` Guilherme G. Piccoli
2016-06-15  8:35     ` Bart Van Assche
2016-06-15 10:10     ` Christoph Hellwig [this message]
2016-06-15 13:09       ` Guilherme G. Piccoli
2016-06-16 15:16         ` Christoph Hellwig
2016-06-25 20:05   ` Alexander Gordeev
2016-06-30 17:48     ` Christoph Hellwig
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
2016-06-23 11:16   ` Alexander Gordeev
2016-06-30 16:54     ` Christoph Hellwig
2016-06-30 17:28       ` Alexander Gordeev
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
2016-06-25 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 ` [PATCH 10/13] blk-mq: only allocate a single mq_map per tag_set Christoph Hellwig
2016-06-14 19:59 ` [PATCH 11/13] blk-mq: allow the driver to pass in an affinity mask Christoph Hellwig
2016-07-04  8:15   ` Alexander Gordeev
2016-07-04  8:38     ` Christoph Hellwig
2016-07-04  9:35       ` Alexander Gordeev
2016-07-10  3:41         ` Christoph Hellwig
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 ` [PATCH 13/13] nvme: remove the post_scan callout Christoph Hellwig
2016-06-16  9:45 ` automatic interrupt affinity for MSI/MSI-X capable devices V2 Bart Van Assche
2016-06-16 15:22   ` Christoph Hellwig
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 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors Christoph Hellwig

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