0m26.188s Running fake test user 45m32.686s user 45m18.552s sys 5m12.465s sys 4m56.468s total 50m45.151s total 50m15.020s % slowdown from mqueue cache thrashing ~8% ~.5% Avg time to send/recv (in nanoseconds per message) when queue empty 305/288 349/318 when queue full (65528 messages) constant priority 526589/823 362/314 increasing priority 403105/916 495/445 decreasing priority 73420/594 482/409 random priority 280147/920 546/436 Time to fill/drain queue (65528 messages, in seconds) constant priority 17.37/.12 .13/.12 increasing priority 4.14/.14 .21/.18 decreasing priority 12.93/.13 .21/.18 random priority 8.88/.16 .22/.17 So, I think the results speak for themselves. It's possible this implementation could be improved by cacheing at least one priority level in the node tree (that would bring the queue empty performance more in line with the old implementation), but this works and is *so* much better than what we had, especially for the common case of a single priority in use, that further refinements can be in follow on patches. [akpm@linux-foundation.org: fix typo in comment, remove stray semicolon] [levinsasha928@gmail.com: use correct gfp flags in msg_insert] Signed-off-by: Doug Ledford Cc: Stephen Rothwell Cc: Manfred Spraul Acked-by: KOSAKI Motohiro Signed-off-by: Sasha Levin Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds ÑO2M™`x