From 0bf377bbb0bea6130f35613491887cc622e42a8b Mon Sep 17 00:00:00 2001 From: Ingo Molnar Date: Sun, 12 Sep 2010 08:14:52 +0200 Subject: [PATCH] sched: Improve latencies under load by decreasing minimum scheduling granularity MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit Mathieu reported bad latencies with make -j10 kind of kbuild workloads - which is mostly caused by us scheduling with a too coarse granularity. Reduce the minimum granularity some more, to make sure we can meet the latency target. I got the following results (make -j10 kbuild load, average of 3 runs): vanilla: maximum latency: 38278.9 µs average latency: 7730.1 µs patched: maximum latency: 22702.1 µs average latency: 6684.8 µs Mathieu also measured it: | | * wakeup-latency.c (SIGEV_THREAD) with make -j10 | | - Mainline 2.6.35.2 kernel | | maximum latency: 45762.1 µs | average latency: 7348.6 µs | | - With only Peter's smaller min_gran (shown below): | | maximum latency: 29100.6 µs | average latency: 6684.1 µs | Reported-by: Mathieu Desnoyers Reported-by: Linus Torvalds Acked-by: Mathieu Desnoyers Suggested-by: Peter Zijlstra Acked-by: Peter Zijlstra LKML-Reference: Signed-off-by: Ingo Molnar --- Reading git-format-patch failed