Neil, On Tue, 16 Jul 2019, Neil Horman wrote: > On Tue, Jul 16, 2019 at 05:57:31PM +0200, Thomas Gleixner wrote: > > On Tue, 16 Jul 2019, Neil Horman wrote: > > > If a cpu has more than this number of interrupts affined to it, they > > > will spill over to other cpus, which potentially may be outside of their > > > affinity mask. > > > > Spill over? > > > > The kernel decides to pick a vector on a CPU outside of the affinity when > > it runs out of vectors on the CPUs in the affinity mask. > > > Yes. > > > Please explain issues technically correct. > > > I don't know what you mean by this. I explained it above, and you clearly > understood it.
It took me a while to grok it. Simply because I first thought it's some hardware issue. And of course after confusion settled I knew what it is, but just because I know that code like the back of my hand. > > > Given that this might cause unexpected behavior on > > > performance sensitive systems, warn the user should this condition occur > > > so that corrective action can be taken > > > > > @@ -244,6 +244,14 @@ __visible unsigned int __irq_entry do_IRQ(struct > > > pt_regs *regs) > > > > Why on earth warn in the interrupt delivery hotpath? Just because it's the > > place which really needs extra instructions and extra cache lines on > > performance sensitive systems, right? > > > Because theres already a check of the same variety in do_IRQ, but if the > information is available outside the hotpath, I was unaware, and am happy to > update this patch to refelct that. Which check are you referring to? Thanks, tglx