On (03/10/07 10:21), Ingo Molnar didst pronounce:
>
> * Mel Gorman <[email protected]> wrote:
>
> > > > Nice one Ingo - got it first try. The problem commit was
> > > > dd41f596cda0d7d6e4a8b139ffdfabcefdd46528 and it's clear that the
> > > > code removed in this commit is put back by this latest patch.
> > > > When applied, profile=sleep works as long as CONFIG_SCHEDSTAT is
> > > > set.
> > > >
> > > And if it isn't set? I can easily see building a new kernel with
> > > stats off and forgetting to change the boot options.
> >
> > If CONFIG_SCHEDSTAT is off and profile=sleep is set, you see with
> > Ingo's patch and readprofile;
> >
> > 0 *unknown*
> > 0 total 0.0000
> >
> > That is a tad confusing hence my follow-up patch which would say
> > "/proc/profile" doesn't exist when readprofile is used and the warning
> > in dmesg.
>
> yep - that's the best we can do for the stable release.
>
Agreed. The less change the better this late in the game.
> We could improve quality of behavior here by not offering /proc/profile
> in that case and by printk-ing something if profile=sleep is specified
> on a !CONFIG_SCHEDSTATS kernel. I'm willing to apply patches that do
> that :)
>
I included a candidate patch in the last mail but it was shoved down at
the bottom so it could easily have been missed.
==============
Subject: 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]>
---
Documentation/kernel-parameters.txt | 3 ++-
kernel/profile.c | 5 +++++
2 files changed, 7 insertions(+), 1 deletion(-)
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc9-005_ingo_profile_fix/Documentation/kernel-parameters.txt linux-2.6.23-rc9-010_document_profilesleep/Documentation/kernel-parameters.txt
--- linux-2.6.23-rc9-005_ingo_profile_fix/Documentation/kernel-parameters.txt 2007-10-02 04:24:52.000000000 +0100
+++ linux-2.6.23-rc9-010_document_profilesleep/Documentation/kernel-parameters.txt 2007-10-02 16:43:41.000000000 +0100
@@ -1395,7 +1395,8 @@ and is between 256 and 4096 characters.
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
processor.max_cstate= [HW,ACPI]
Limit processor to maximum C-state
diff -rup -X /usr/src/patchset-0.6/bin//dontdiff linux-2.6.23-rc9-005_ingo_profile_fix/kernel/profile.c linux-2.6.23-rc9-010_document_profilesleep/kernel/profile.c
--- linux-2.6.23-rc9-005_ingo_profile_fix/kernel/profile.c 2007-10-02 04:24:52.000000000 +0100
+++ linux-2.6.23-rc9-010_document_profilesleep/kernel/profile.c 2007-10-02 16:44:50.000000000 +0100
@@ -60,6 +60,7 @@ static int __init profile_setup(char * s
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 * s
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)] == ',')
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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