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

[tip-bot for Ingo Molnar]

Commit-ID:  98e4833ba3c314c99dc364012fba6ac894230ad0
Gitweb:     http://git.kernel.org/tip/98e4833ba3c314c99dc364012fba6ac894230ad0
Author:     Ingo Molnar <mingo@xxxxxxx>
AuthorDate: Mon, 23 Nov 2009 08:03:09 +0100
Committer:  Ingo Molnar <mingo@xxxxxxx>
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@xxxxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Cc: Mike Galbraith <efault@xxxxxx>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 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;
 
  out_kill:
--
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