Jes,
I am all in favor of making the automatic setup better, but assuming an
automatic setup is always right seems problematic. There could be
workloads where you may want to assign affinity explicitly.
Adding Thomas to the thread.
My understanding that the thought is to prevent user-space from
messing up the nice linear assignment, but maybe this might be too
conservative?
The patch that prevented user-space from touching managed irq affinity
assignments:
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commit 45ddcecbfa947f1dd8e8019bad9e90d6c9f2665c
Author: Thomas Gleixner <t...@linutronix.de>
Date: Mon Jul 4 17:39:25 2016 +0900
genirq: Use affinity hint in irqdesc allocation
Use the affinity hint in the irqdesc allocator. The hint is used to
determine
the node for the allocation and to set the affinity of the interrupt.
If multiple interrupts are allocated (multi-MSI) then the allocator
iterates
over the cpumask and for each set cpu it allocates on their node
and sets the
initial affinity to that cpu.
If a single interrupt is allocated (MSI-X) then the allocator uses
the first
cpu in the mask to compute the allocation node and uses the mask
for the
initial affinity setting.
Interrupts set up this way are marked with the AFFINITY_MANAGED flag to
prevent userspace from messing with their affinity settings.
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: Christoph Hellwig <h...@lst.de>
Cc: linux-bl...@vger.kernel.org
Cc: linux-...@vger.kernel.org
Cc: linux-n...@lists.infradead.org
Cc: ax...@fb.com
Cc: agord...@redhat.com
Link:
http://lkml.kernel.org/r/1467621574-8277-5-git-send-email-...@lst.de
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
--
