On Thu, 10 Nov 2016, Jason A. Donenfeld wrote: > On Thu, Nov 10, 2016 at 10:03 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > > Does the slowdown come from the kmalloc overhead or mostly from the less > > efficient code? > > > > If it's mainly kmalloc, then you can preallocate the buffer once for the > > kthread you're running in and be done with it. If it's the code, then bad > > luck. > > I fear both. GCC can optimize stack variables in ways that it cannot > optimize various memory reads and writes. The question is how much of it is code and how much of it is the kmalloc. > Strangely, the solution that appeals to me most at the moment is to > kmalloc (or vmalloc?) a new stack, copy over thread_info, and fiddle > with the stack registers. I don't see any APIs, however, for a > platform independent way of doing this. And maybe this is a horrible > idea. But at least it'd allow me to keep my stack-based code the > same... Do not even think about going there. That's going to be a major mess. As a short time workaround you can increase THREAD_SIZE_ORDER for now and then fix it proper with switching to seperate irq stacks. Thanks, tglx
