Hi, 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). Today I decided to finally hunt down the problem, so I created a synthetic test that basically consists on copying a bunch of files from one drive to another (from an SSD to an external USB 3.0). This is pretty similar to what I noticed; the graphical interface slows down. Then I bisected the issue and it turns out that indeed it wasn't happening in the past, it started happening in v3.11, and it was triggered by this commit: e2be15f (mm: vmscan: stall page reclaim and writeback pages based on dirty/writepage pages encountered) 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); After that I don't notice the slow down any more. Anybody has any ideas how to fix the issue properly? -- 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>