On Fri, Aug 09, 2013 at 06:26:37PM +0900, Joonsoo Kim wrote: > If parallel fault occur, we can fail to allocate a hugepage, > because many threads dequeue a hugepage to handle a fault of same address. > This makes reserved pool shortage just for a little while and this cause > faulting thread who can get hugepages to get a SIGBUS signal. > > To solve this problem, we already have a nice solution, that is, > a hugetlb_instantiation_mutex. This blocks other threads to dive into > a fault handler. This solve the problem clearly, but it introduce > performance degradation, because it serialize all fault handling. > > Now, I try to remove a hugetlb_instantiation_mutex to get rid of > performance degradation. For achieving it, at first, we should ensure that > no one get a SIGBUS if there are enough hugepages. > > For this purpose, if we fail to allocate a new hugepage when there is > concurrent user, we return just 0, instead of VM_FAULT_SIGBUS. With this, > these threads defer to get a SIGBUS signal until there is no > concurrent user, and so, we can ensure that no one get a SIGBUS if there > are enough hugepages. > > Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com> >
Hello, David. May I ask to you to review this one? I guess that you already thought about the various race condition, so I think that you are the most appropriate reviewer to this patch. :) Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
