On Sat, Jul 15, 2017 at 8:55 AM, Mel Gorman <mgorman@xxxxxxx> wrote: > The patch looks fine to be but when writing the patch, I wondered why the > original code disabled preemption before inc_mm_tlb_gen. I didn't spot > the reason for it but given the importance of properly synchronising with > switch_mm, I played it safe. However, this should be ok on top and > maintain the existing sequences LGTM. You could also fold it into your patch or even put it before your patch, too. FWIW, I didn't have any real reason to inc_mm_tlb_gen() with preemption disabled. I think I did it because the code it replaced was also called with preemption off. That being said, it's effectively a single instruction, so it barely matters latency-wise. (Hmm. Would there be a performance downside if a thread got preempted between inc_mm_tlb_gen() and doing the flush? It could arbitrarily delay the IPIs, which would give a big window for something else to flush and maybe make our IPIs unnecessary. Whether that's a win or a loss isn't so clear to me.) -- 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>
