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authorMel Gorman <mel@csn.ul.ie>2007-10-24 18:23:50 +0200
committerIngo Molnar <mingo@elte.hu>2007-10-24 18:23:50 +0200
commitb3da2a73ff5a2953a4ad8ebbf0aa7e6965ff9de2 (patch)
tree43583e5f492a48c56f9537006c8f806d570b0d84
parent838225b48edc971620cbeb292034dabd2b0d7d1d (diff)
downloadlinux-b3da2a73ff5a2953a4ad8ebbf0aa7e6965ff9de2.tar.gz
sched: document profile=sleep requiring CONFIG_SCHEDSTATS
profile=sleep only works if CONFIG_SCHEDSTATS is set. This patch notes
the limitation in Documentation/kernel-parameters.txt and prints a
warning at boot-time if profile=sleep is used without CONFIG_SCHEDSTAT.

Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
-rw-r--r--Documentation/kernel-parameters.txt3
-rw-r--r--kernel/profile.c5
2 files changed, 7 insertions, 1 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index a13d69b2217d..8ae5fac08dfa 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1444,7 +1444,8 @@ and is between 256 and 4096 characters. It is defined in the file
 			Param: "schedule" - profile schedule points.
 			Param: <number> - step/bucket size as a power of 2 for
 				statistical time based profiling.
-			Param: "sleep" - profile D-state sleeping (millisecs)
+			Param: "sleep" - profile D-state sleeping (millisecs).
+				Requires CONFIG_SCHEDSTATS
 			Param: "kvm" - profile VM exits.
 
 	processor.max_cstate=	[HW,ACPI]
diff --git a/kernel/profile.c b/kernel/profile.c
index 631b75c25d7e..5e95330e5120 100644
--- a/kernel/profile.c
+++ b/kernel/profile.c
@@ -60,6 +60,7 @@ static int __init profile_setup(char * str)
 	int par;
 
 	if (!strncmp(str, sleepstr, strlen(sleepstr))) {
+#ifdef CONFIG_SCHEDSTATS
 		prof_on = SLEEP_PROFILING;
 		if (str[strlen(sleepstr)] == ',')
 			str += strlen(sleepstr) + 1;
@@ -68,6 +69,10 @@ static int __init profile_setup(char * str)
 		printk(KERN_INFO
 			"kernel sleep profiling enabled (shift: %ld)\n",
 			prof_shift);
+#else
+		printk(KERN_WARNING
+			"kernel sleep profiling requires CONFIG_SCHEDSTATS\n");
+#endif /* CONFIG_SCHEDSTATS */
 	} else if (!strncmp(str, schedstr, strlen(schedstr))) {
 		prof_on = SCHED_PROFILING;
 		if (str[strlen(schedstr)] == ',')