[tip:tracing/core] ring-buffer benchmark: Run producer/consumer threads at nice +19

tip-bot for Ingo Molnar
2009-11-23T07:16:24Z

Commit-ID: 98e4833ba3c314c99dc364012fba6ac894230ad0
Gitweb: http://git.kernel.org/tip/98e4833ba3c314c99dc364012fba6ac894230ad0
Author: Ingo Molnar <mingo@elte.hu>
AuthorDate: Mon, 23 Nov 2009 08:03:09 +0100
Committer: Ingo Molnar <mingo@elte.hu>
CommitDate: Mon, 23 Nov 2009 08:03:09 +0100

ring-buffer benchmark: Run producer/consumer threads at nice +19

The ring-buffer benchmark threads run on nice 0 by default, using
up a lot of CPU time and slowing down the system:

PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
1024 root 20 0 0 0 0 D 95.3 0.0 4:01.67 rb_producer
1023 root 20 0 0 0 0 R 93.5 0.0 2:54.33 rb_consumer
21569 mingo 40 0 14852 1048 772 R 3.6 0.1 0:00.05 top
1 root 40 0 4080 928 668 S 0.0 0.0 0:23.98 init

Renice them to +19 to make them less intrusive.

Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Galbraith <efault@gmx.de>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
kernel/trace/ring_buffer_benchmark.c | 6 ++++++
1 files changed, 6 insertions(+), 0 deletions(-)

diff --git a/kernel/trace/ring_buffer_benchmark.c b/kernel/trace/ring_buffer_benchmark.c
index 70df73e..3875d49 100644
--- a/kernel/trace/ring_buffer_benchmark.c
+++ b/kernel/trace/ring_buffer_benchmark.c
@@ -399,6 +399,12 @@ static int __init ring_buffer_benchmark_init(void)
if (IS_ERR(producer))
goto out_kill;

+ /*
+ * Run them as low-prio background tasks by default:
+ */
+ set_user_nice(consumer, 19);
+ set_user_nice(producer, 19);
+
return 0;