Messages in this thread |  | | | Date | Tue, 24 Nov 2009 09:57:03 -0800 (PST) | | Subject | Re: [PATCH v2] irq: Add node_affinity CPU masks for smarter irqbalance hints | | From | David Miller <> |
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From: Thomas Gleixner <tglx@linutronix.de> Date: Tue, 24 Nov 2009 12:07:35 +0100 (CET)
> And what does the kernel do with this information and why are we not > using the existing device/numa_node information ?
It's a different problem space Thomas.
If the device lives on NUMA node X, we still end up wanting to allocate memory resources (RX ring buffers) on other NUMA nodes on a per-queue basis.
Otherwise a network card's forwarding performance is limited by the memory bandwidth of a single NUMA node, and on a multiqueue cards we therefore fare much better by allocating each device RX queue's memory resources on a different NUMA node.
It is this NUMA usage that PJ is trying to export somehow to userspace so that irqbalanced and friends can choose the IRQ cpu masks more intelligently.
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