Re: [PATCH 07/14] genirq: Add a new generic IPI reservation code to irq core

From: Qais Yousef
Date: Mon Nov 09 2015 - 05:12:14 EST


On 11/07/2015 01:31 PM, Thomas Gleixner wrote:
On Tue, 3 Nov 2015, Qais Yousef wrote:
+
+ /* always allocate a virq per cpu */
+ nr_irqs = ipi_mask_weight(dest);
That's not really a good assumption. Not all architectures need
seperate interrupt numbers / descriptors because they can allocate
from a per cpu interrupt space. We really want to handle that here as
well. So we need a flag in the IPI domain which tells us whether that
allocation needs to be weight(desc) or 1.

OK. But is it bad to always allocate the weight? I thought allocating virqs is cheap, or maybe not?

Thanks,
Qais
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