From: keith.busch@intel.com (Keith Busch)
Subject: Why NVMe MSIx vectors affinity set across NUMA nodes?
Date: Mon, 22 Jan 2018 10:14:37 -0700 [thread overview]
Message-ID: <20180122171437.GL12043@localhost.localdomain> (raw)
In-Reply-To: <CAKTKpr6V=UPtRRApvQ_TAEuRQB8qqgvDmaaXFjch4wpZUqoAfw@mail.gmail.com>
On Mon, Jan 22, 2018@09:55:55AM +0530, Ganapatrao Kulkarni wrote:
> Hi,
>
> I have observed that NVMe driver splitting interrupt affinity of MSIx
> vectors among available NUMA nodes,
> any specific reason for that?
>
> i see this is happening due to pci flag PCI_IRQ_AFFINITY is set in
> function nvme_setup_io_queues
>
> nr_io_queues = pci_alloc_irq_vectors(pdev, 1, nr_io_queues,
> PCI_IRQ_ALL_TYPES | PCI_IRQ_AFFINITY);
>
> IMO, having all vectors on same node CPUs improves interrupt latency
> than distributing among all nodes.
What affinity maps are you seeing? It's not supposed to share one vector
across two NUMA nodes, unless you simply don't have enough vectors.
next prev parent reply other threads:[~2018-01-22 17:14 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-22 4:25 Why NVMe MSIx vectors affinity set across NUMA nodes? Ganapatrao Kulkarni
2018-01-22 17:14 ` Keith Busch [this message]
2018-01-22 17:22 ` Ganapatrao Kulkarni
2018-01-22 17:32 ` Keith Busch
2018-01-22 17:55 ` Ganapatrao Kulkarni
2018-01-22 18:05 ` Keith Busch
2018-01-22 18:12 ` Ganapatrao Kulkarni
2018-01-22 18:20 ` Keith Busch
2018-01-23 13:30 ` Sagi Grimberg
2018-01-24 2:17 ` Ganapatrao Kulkarni
2018-01-24 15:48 ` Keith Busch
2018-01-24 19:39 ` Sagi Grimberg
2018-01-24 20:38 ` Keith Busch
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