On 08/23/2017 07:49 AM, Liang, Kan wrote: >> On Tue, Aug 22, 2017 at 12:55 PM, Liang, Kan <kan.li...@intel.com> wrote: >>> >>>> So I propose testing the attached trivial patch. >>> >>> It doesn’t work. >>> The call stack is the same. >> >> So I would have expected the stack trace to be the same, and I would even >> expect the CPU usage to be fairly similar, because you'd see repeating from >> the callers (taking the fault again if the page is - once again - being >> migrated). >> >> But I was hoping that the wait queues would be shorter because the loop for >> the retry would be bigger. >> >> Oh well. >> >> I'm slightly out of ideas. Apparently the yield() worked ok (apart from not >> catching all cases), and maybe we could do a version that waits on the page >> bit in the non-contended case, but yields under contention? >> >> IOW, maybe this is the best we can do for now? Introducing that >> "wait_on_page_migration()" helper might allow us to tweak this a bit as >> people come up with better ideas.. > > The "wait_on_page_migration()" helper works well in the overnight testing. >
Linus, Will you still consider the original patch as a fail safe mechanism? Thanks. Tim
