From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Gleixner Date: Mon, 26 Oct 2020 23:49:35 +0100 Subject: [Intel-wired-lan] [PATCH v4 4/4] PCI: Limit pci_alloc_irq_vectors() to housekeeping CPUs In-Reply-To: <959997ee-f393-bab0-45c0-4144c37b9185@redhat.com> References: <20201019111137.GL2628@hirez.programming.kicks-ass.net> <20201019140005.GB17287@fuller.cnet> <20201020073055.GY2611@hirez.programming.kicks-ass.net> <078e659e-d151-5bc2-a7dd-fe0070267cb3@redhat.com> <20201020134128.GT2628@hirez.programming.kicks-ass.net> <6736e643-d4ae-9919-9ae1-a73d5f31463e@redhat.com> <260f4191-5b9f-6dc1-9f11-085533ac4f55@redhat.com> <20201023085826.GP2611@hirez.programming.kicks-ass.net> <9ee77056-ef02-8696-5b96-46007e35ab00@redhat.com> <87ft6464jf.fsf@nanos.tec.linutronix.de> <20201026173012.GA377978@fuller.cnet> <875z6w4xt4.fsf@nanos.tec.linutronix.de> <86f8f667-bda6-59c4-91b7-6ba2ef55e3db@intel.com> <87v9ew3fzd.fsf@nanos.tec.linutronix.de> <85b5f53e-5be2-beea-269a-f70029bea298@intel.com> <87lffs3bd6.fsf@nanos.tec.linutronix.de> <959997ee-f393-bab0-45c0-4144c37b9185@redhat.com> Message-ID: <875z6w38n4.fsf@nanos.tec.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: intel-wired-lan@osuosl.org List-ID: On Mon, Oct 26 2020 at 18:22, Nitesh Narayan Lal wrote: > On 10/26/20 5:50 PM, Thomas Gleixner wrote: >> But I still think that for curing that isolation stuff we want at least >> some information from the driver. Alternative solution would be to grant >> the allocation of interrupts and queues and have some sysfs knob to shut >> down queues at runtime. If that shutdown results in releasing the queue >> interrupt (via free_irq()) then the vector exhaustion problem goes away. > > I think this is close to what I and Marcelo were discussing earlier today > privately. > > I don't think there is currently a way to control the enablement/disablement of > interrupts from the userspace. You cannot just disable the interrupt. You need to make sure that the associated queue is shutdown or quiesced _before_ the interrupt is shut down. Thanks, tglx