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 <[email protected]> Signed-off-by: Ingo Molnar <[email protected]>
kawasaki · Oct 24, 2007 · b3da2a7 · b3da2a7
1 parent 838225b
commit b3da2a7
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Showing 2 changed files with 7 additions and 1 deletion.
diff --git 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
@@ -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)] == ',')