* Rik van Riel <r...@surriel.com> wrote:
> On Mon, 2018-07-16 at 01:04 +0200, Ingo Molnar wrote: > > * Rik van Riel <r...@surriel.com> wrote: > > > > > + /* > > > + * Stop remote flushes for the previous mm. > > > + * Skip the idle task; we never send init_mm TLB > > > flushing IPIs, > > > + * but the bitmap manipulation can cause cache > > > line contention. > > > + */ > > > + if (real_prev != &init_mm) { > > > + VM_WARN_ON_ONCE(!cpumask_test_cpu(cpu, > > > + mm_cpumask(real_pr > > > ev))); > > > + cpumask_clear_cpu(cpu, > > > mm_cpumask(real_prev)); > > > > BTW., could this optimization be (safely) extended to all (or most) > > !task->mm > > kernel threads? > > > > In particular softirq and threaded irq handlers could benefit greatly > > I suspect in > > certain networking intense workloads that happen to active them. > > Yes, it could. > > Are there kernel threads that use something other than > init_mm today? Yeah, I think that's the typical case - so at minimum the comment should be fixed: > > > + * Skip the idle task; we never send init_mm TLB flushing IPIs, and it should say 'skip kernel threads', right? Thanks, Ingo