On Thu, Mar 19, 2015 at 7:10 AM, Mel Gorman <mgorman@xxxxxxx> wrote: > - if (!pmd_dirty(pmd)) > + /* See similar comment in do_numa_page for explanation */ > + if (!(vma->vm_flags & VM_WRITE)) Yeah, that would certainly be a whole lot more obvious than all the "if this particular pte/pmd looks like X" tests. So that, together with scanning rate improvements (this *does* seem to be somewhat chaotic, so it's quite possible that the current scanning rate thing is just fairly unstable) is likely the right thing. I'd just like to _understand_ why that write/dirty bit makes such a difference. I thought I understood what was going on, and was happy, and then Dave come with his crazy numbers. Damn you Dave, and damn your numbers and "facts" and stuff. Sometimes I much prefer ignorant bliss. Linus -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>