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Date: Mon, 30 Nov 2009 09:24:02 -0800 From: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com> To: Thomas Gleixner <tglx@...utronix.de> Cc: David Miller <davem@...emloft.net>, "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "arjan@...ux.jf.intel.com" <arjan@...ux.jf.intel.com>, "mingo@...e.hu" <mingo@...e.hu>, "yong.zhang0@...il.com" <yong.zhang0@...il.com>, "netdev@...r.kernel.org" <netdev@...r.kernel.org> Subject: Re: [PATCH v2] irq: Add node_affinity CPU masks for smarter irqbalance hints On Tue, 2009-11-24 at 14:23 -0800, Thomas Gleixner wrote: > On Tue, 24 Nov 2009, Peter P Waskiewicz Jr wrote: > > On Tue, 2009-11-24 at 13:56 -0800, Thomas Gleixner wrote: > > > On Tue, 24 Nov 2009, David Miller wrote: > > > > > > > From: Thomas Gleixner <tglx@...utronix.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. > > > > > > So you need a preferred irq mask information on a per IRQ basis and > > > that mask is not restricted to the CPUs of a single NUMA node, right ? > > > > > Just to clarify, I need a preferred CPU mask on a per IRQ basis. And > > yes, that mask may not be restricted to the CPUs of a single NUMA node. > > But in the normal case, the mask will be restricted to CPUs of a single > > node. > > Right, but the normal case does not help much if we need to consider > the special case of multiple nodes affected which requires another > cpumask in irq_desc. That's what I really want to avoid. > > I at least understand the exact problem you guys want to solve. Will > think more about it. > Just a friendly ping Thomas. Any progress on your thinking about this proposal? Cheers, -PJ -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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