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Date: Tue, 24 Nov 2009 13:17:50 +0800 From: Yong Zhang <yong.zhang0@...il.com> To: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@...el.com> Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>, "arjan@...ux.jf.intel.com" <arjan@...ux.jf.intel.com>, "davem@...emloft.net" <davem@...emloft.net>, "netdev@...r.kernel.org" <netdev@...r.kernel.org> Subject: Re: [PATCH] irq: Add node_affinity CPU masks for smarter irqbalance hints [snip] >> >> 1) I think you should consider CONFIG_CPUMASK_OFFSTACK which will affect >> node_affinity. >> 2) It seems like this patch can't work with SPARSE_IRQ. > > This mechanism isn't going to be used by any internal kernel mechanism > for determining interrupt placement or operation. It's purely something > that either a driver can modify, or external script (through /proc), > that irqbalance will make use of. If irqbalance isn't running, or the > current version of irqbalance doesn't support reading node_affinity, > then it won't affect the system's operation. > > If irqbalance does support it, it'll read whatever the supplied mask is, > and then will try and balance interrupts within that mask. It will bail > if the mask is invalid, or won't apply to the running system, just like > how putting a bogus mask into smp_affinity is ignored. > > If there's something I'm missing beyond this with the two suggestions > you've made (I looked into those two parameters and tried to draw > conclusions), please let me know. My two suggestions are both about your adding node_affinity. Before you can use this element, you must initialise it firstly. You can refer how irq_desc::affinity is used in function alloc_desc_masks(). include/linux/irq.h: static inline bool alloc_desc_masks(struct irq_desc *desc, int node, bool boot) { gfp_t gfp = GFP_ATOMIC; if (boot) gfp = GFP_NOWAIT; #ifdef CONFIG_CPUMASK_OFFSTACK if (!alloc_cpumask_var_node(&desc->affinity, gfp, node)) return false; #ifdef CONFIG_GENERIC_PENDING_IRQ if (!alloc_cpumask_var_node(&desc->pending_mask, gfp, node)) { free_cpumask_var(desc->affinity); return false; } #endif #endif return true; } Thanks, Yong > > Cheers, > -PJ Waskiewicz > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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