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Groups > linux.kernel > #1422275
| From | Christoph Hellwig <hch@lst.de> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 09/13] blk-mq: don't redistribute hardware queues on a CPU hotplug event |
| Date | 2016-06-14 22:10 +0200 |
| Message-ID | <rK2OS-1aP-15@gated-at.bofh.it> (permalink) |
| References | <rK2Fb-Rz-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
Currently blk-mq will totally remap hardware context when a CPU hotplug even happened, which causes major havoc for drivers, as they are never told about this remapping. E.g. any carefully sorted out CPU affinity will just be completely messed up. The rebuild also doesn't really help for the common case of cpu hotplug, which is soft onlining / offlining of cpus - in this case we should just leave the queue and irq mapping as is. If it actually worked it would have helped in the case of physical cpu hotplug, although for that we'd need a way to actually notify the driver. Note that drivers may already be able to accommodate such a topology change on their own, e.g. using the reset_controller sysfs file in NVMe will cause the driver to get things right for this case. With the rebuild removed we will simplify retain the queue mapping for a soft offlined CPU that will work when it comes back online, and will map any newly onlined CPU to queue NULL until the driver initiates a rebuild of the queue map. Signed-off-by: Christoph Hellwig <hch@lst.de> --- block/blk-mq.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index bc7166d..f972d32 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -2114,8 +2114,6 @@ static void blk_mq_queue_reinit(struct request_queue *q, blk_mq_sysfs_unregister(q); - blk_mq_update_queue_map(q->mq_map, q->nr_hw_queues, online_mask); - /* * redo blk_mq_init_cpu_queues and blk_mq_init_hw_queues. FIXME: maybe * we should change hctx numa_node according to new topology (this -- 2.1.4
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automatic interrupt affinity for MSI/MSI-X capable devices V2 Christoph Hellwig <hch@lst.de> - 2016-06-14 22:00 +0200
[PATCH 03/13] irq: Add affinity hint to irq allocation Christoph Hellwig <hch@lst.de> - 2016-06-14 22:00 +0200
[PATCH 11/13] blk-mq: allow the driver to pass in an affinity mask Christoph Hellwig <hch@lst.de> - 2016-06-14 22:00 +0200
[PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors Christoph Hellwig <hch@lst.de> - 2016-06-14 22:00 +0200
Re: [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> - 2016-06-15 00:00 +0200
Re: [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors Christoph Hellwig <hch@lst.de> - 2016-06-15 12:20 +0200
Re: [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors "Guilherme G. Piccoli" <gpiccoli@linux.vnet.ibm.com> - 2016-06-15 15:10 +0200
Re: [PATCH 06/13] irq: add a helper spread an affinity mask for MSI/MSI-X vectors Christoph Hellwig <hch@lst.de> - 2016-06-16 17:20 +0200
[PATCH 07/13] pci: Provide sensible irq vector alloc/free routines Christoph Hellwig <hch@lst.de> - 2016-06-14 22:00 +0200
Re: [PATCH 07/13] pci: Provide sensible irq vector alloc/free routines Alexander Gordeev <agordeev@redhat.com> - 2016-06-23 13:20 +0200
[PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig <hch@lst.de> - 2016-06-14 22:00 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig <hch@lst.de> - 2016-06-15 12:30 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Keith Busch <keith.busch@intel.com> - 2016-06-15 17:10 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Keith Busch <keith.busch@intel.com> - 2016-06-15 18:00 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Keith Busch <keith.busch@intel.com> - 2016-06-15 22:00 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Keith Busch <keith.busch@intel.com> - 2016-06-15 22:10 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Keith Busch <keith.busch@intel.com> - 2016-06-16 17:20 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Alexander Gordeev <agordeev@redhat.com> - 2016-06-22 14:00 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig <hch@lst.de> - 2016-06-16 17:30 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig <hch@lst.de> - 2016-06-20 14:30 +0200
Re: [PATCH 02/13] irq: Introduce IRQD_AFFINITY_MANAGED flag Christoph Hellwig <hch@lst.de> - 2016-06-21 16:40 +0200
[PATCH 01/13] irq/msi: Remove unused MSI_FLAG_IDENTITY_MAP Christoph Hellwig <hch@lst.de> - 2016-06-14 22:00 +0200
[PATCH 09/13] blk-mq: don't redistribute hardware queues on a CPU hotplug event Christoph Hellwig <hch@lst.de> - 2016-06-14 22:10 +0200
[PATCH 13/13] nvme: remove the post_scan callout Christoph Hellwig <hch@lst.de> - 2016-06-14 22:10 +0200
[PATCH 08/13] pci: spread interrupt vectors in pci_alloc_irq_vectors Christoph Hellwig <hch@lst.de> - 2016-06-14 22:10 +0200
[PATCH 05/13] irq/msi: Make use of affinity aware allocations Christoph Hellwig <hch@lst.de> - 2016-06-14 22:10 +0200
[PATCH 12/13] nvme: switch to use pci_alloc_irq_vectors Christoph Hellwig <hch@lst.de> - 2016-06-14 22:10 +0200
[PATCH 04/13] irq: Use affinity hint in irqdesc allocation Christoph Hellwig <hch@lst.de> - 2016-06-14 22:10 +0200
Re: automatic interrupt affinity for MSI/MSI-X capable devices V2 Christoph Hellwig <hch@lst.de> - 2016-06-16 17:30 +0200
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