On Thu, Jun 5, 2014 at 8:37 AM, Michal Hocko <mhocko@xxxxxxx> wrote: > On Thu 05-06-14 06:33:40, Felipe Contreras wrote: >> For a while I've noticed that my machine bogs down in certain >> situations, usually while doing heavy I/O operations, it is not just the >> I/O operations, but everything, including the graphical interface, even >> the mouse pointer. >> >> As far as I can recall this did not happen in the past. >> >> I noticed this specially on certain operations, for example updating a >> a game on Steam (to an exteranl USB 3.0 device), or copying TV episodes >> to a USB memory stick (probably flash-based). > > We had a similar report for opensuse. The common part was that there was > an IO to a slow USB device going on. Well, it's a USB 3.0 device, I can write at 250 MB/s, so it's not really that slow. And in fact, when I read and write to and from the same USB 3.0 device, I don't see the issue. >> Then I went back to the latest stable version (v3.14.5), and commented >> out the line I think is causing the slow down: >> >> if (nr_unqueued_dirty == nr_taken || nr_immediate) >> congestion_wait(BLK_RW_ASYNC, HZ/10); > > Yes, I came to the same check. I didn't have any confirmation yet so > thanks for your confirmation. I've suggested to reduce this > congestion_wait only to kswapd: > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 32c661d66a45..ef6a1c0e788c 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1566,7 +1566,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec, > * implies that pages are cycling through the LRU faster than > * they are written so also forcibly stall. > */ > - if (nr_unqueued_dirty == nr_taken || nr_immediate) > + if ((nr_unqueued_dirty == nr_taken || nr_immediate) && current_is_kswapd()) > congestion_wait(BLK_RW_ASYNC, HZ/10); > } Unfortunately that doesn't fix the issue for me. -- Felipe Contreras -- 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>