Hi Mel, 2016-06-03 14:36 GMT+02:00 Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>: > On Fri, Jun 03, 2016 at 01:57:06PM +0200, Marcin Wojtas wrote: >> >> For the record: the newest kernel I was able to reproduce the dumps >> >> was v4.6: http://pastebin.com/ekDdACn5. I've just checked v4.7-rc1, >> >> which comprise a lot (mainly yours) changes in mm, and I'm wondering >> >> if there may be a spot fix or rather a series of improvements. I'm >> >> looking forward to your opinion and would be grateful for any advice. >> >> >> > >> > I don't believe we want to reintroduce the reserve to cope with CMA. One >> > option would be to widen the gap between low and min watermark by the >> > size of the CMA region. The effect would be to wake kswapd earlier which >> > matters considering the context of the failing allocation was >> > GFP_ATOMIC. >> >> Of course my intention is not reintroducing anything that's gone >> forever, but just to find out way to overcome current issues. Do you >> mean increasing CMA size? > > No. There is a gap between the low and min watermarks. At the low point, > kswapd is woken up and at the min point allocation requests either > either direct reclaim or fail if they are atomic. What I'm suggesting > is that you adjust the low watermark and add the size of the CMA area > to it so that kswapd is woken earlier. The watermarks are calculated in > __setup_per_zone_wmarks > I printed all zones' settings, whose watermarks are configured within __setup_per_zone_wmarks(). There are three DMA, Normal and Movable - only first one's watermarks have non-zero values. Increasing DMA min watermark didn't help. I also played with increasing /proc/sys/vm/min_free_kbytes from ~2560 to 16000 (__setup_per_zone_wmarks() recalculates watermarks after that) - no effect either. Best regards, Marcin -- 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>