svn commit: r281983 - head/sys/cddl/dev/profile
Robert Watson
rwatson at FreeBSD.org
Sat Apr 25 15:43:13 UTC 2015
Author: rwatson
Date: Sat Apr 25 15:43:12 2015
New Revision: 281983
URL: https://svnweb.freebsd.org/changeset/base/281983
Log:
Adjust PROF_ARTIFICIAL_FRAMES in the DTrace profile provider on ARM to
skip 10, rather than 9, frames. This appears to work quite well in
practice on the BeagleBone Black, so remove a comment about the value
being bogus and replace it with a slightly less negative one. However,
the number of frames to skip is quite sensitive to details of the timer
and interrupt handling paths, so this is necessarily fragile -- but no
more so than on x86.
Sponsored by: DARPA, AFRL
Modified:
head/sys/cddl/dev/profile/profile.c
Modified: head/sys/cddl/dev/profile/profile.c
==============================================================================
--- head/sys/cddl/dev/profile/profile.c Sat Apr 25 13:34:25 2015 (r281982)
+++ head/sys/cddl/dev/profile/profile.c Sat Apr 25 15:43:12 2015 (r281983)
@@ -134,8 +134,10 @@ struct profile_probe_percpu;
#endif
#ifdef __arm__
-/* bogus */
-#define PROF_ARTIFICIAL_FRAMES 9
+/*
+ * At least on ARMv7, this appears to work quite well.
+ */
+#define PROF_ARTIFICIAL_FRAMES 10
#endif
typedef struct profile_probe {
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