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Shankar" , Andi Kleen , linuxppc-dev@lists.ozlabs.org, x86@kernel.org, Ricardo Neri , Stephane Eranian , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, Tony Luck , Nicholas Piggin , Andrew Morton , David Woodhouse X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Fri, May 06, 2022 at 09:48:28PM +0200, Thomas Gleixner wrote: > Ricardo, Thank you very much for your feedback Thomas! I am sorry for my late reply, I had been out of office. > > On Thu, May 05 2022 at 16:59, Ricardo Neri wrote: > > Certain types of interrupts, such as NMI, do not have an associated vector. > > They, however, target specific CPUs. Thus, when assigning the destination > > CPU, it is beneficial to select the one with the lowest number of > > vectors. > > Why is that beneficial especially in the context of a NMI watchdog which > then broadcasts the NMI to all other CPUs? My intent was not the NMI watchdog specifically but potential use cases that do not involve NMI broadcasts. If the NMI targets a single CPU, it is best to select the CPU with the lowest vector allocation count. > > That's wishful thinking perhaps, but I don't see any benefit at all. > > > Prepend the functions matrix_find_best_cpu_managed() and > > matrix_find_best_cpu_managed() > > The same function prepended twice becomes two functions :) > Sorry, I missed this. > > with the irq_ prefix and expose them for > > IRQ controllers to use when allocating and activating vector-less IRQs. > > There is no such thing like a vectorless IRQ. NMIs have a vector. Can we > please describe facts and not pulled out of thin air concepts which do > not exist? Thank you for the clarification. I see your point. I wrote this patch because maskable interrupts and NMIs have different entry points. As you state, however, the also have a vector. I can drop this patch. BR, Ricardo > > Thanks, > > tglx _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu