From ecf3965dfa88f396aa240ba433cf39ebe5328eb0 Mon Sep 17 00:00:00 2001
From: andrew <andrew@FreeBSD.org>
Date: Sat, 5 Dec 2015 10:00:01 +0000
Subject: [PATCH] Allow the artificial profile frames to be adjusted as needed
 by the user. While here update for armv6 to a tested value.

Submitted by:	Howard Su <howard0su@gmail.com>
Reviewed by:	stat
Differential Revision:	https://reviews.freebsd.org/D4315
---
 sys/cddl/dev/profile/profile.c | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/sys/cddl/dev/profile/profile.c b/sys/cddl/dev/profile/profile.c
index 80a0eca9eaec..4deac8710dc7 100644
--- a/sys/cddl/dev/profile/profile.c
+++ b/sys/cddl/dev/profile/profile.c
@@ -50,6 +50,7 @@
 #include <sys/proc.h>
 #include <sys/selinfo.h>
 #include <sys/smp.h>
+#include <sys/sysctl.h>
 #include <sys/uio.h>
 #include <sys/unistd.h>
 #include <machine/cpu.h>
@@ -134,10 +135,7 @@ struct profile_probe_percpu;
 #endif
 
 #ifdef __arm__
-/*
- * At least on ARMv7, this appears to work quite well.
- */
-#define	PROF_ARTIFICIAL_FRAMES	10
+#define	PROF_ARTIFICIAL_FRAMES	3
 #endif
 
 #ifdef __aarch64__
@@ -233,7 +231,12 @@ static dtrace_pops_t profile_pops = {
 static struct cdev		*profile_cdev;
 static dtrace_provider_id_t	profile_id;
 static hrtime_t			profile_interval_min = NANOSEC / 5000;	/* 5000 hz */
-static int			profile_aframes = 0;			/* override */
+static int			profile_aframes = PROF_ARTIFICIAL_FRAMES;
+
+SYSCTL_DECL(_kern_dtrace);
+SYSCTL_NODE(_kern_dtrace, OID_AUTO, profile, CTLFLAG_RD, 0, "DTrace profile parameters");
+SYSCTL_INT(_kern_dtrace_profile, OID_AUTO, aframes, CTLFLAG_RW, &profile_aframes,
+    0, "Skipped frames for profile provider");
 
 static sbintime_t
 nsec_to_sbt(hrtime_t nsec)
@@ -352,7 +355,7 @@ profile_create(hrtime_t interval, char *name, int kind)
 	prof->prof_kind = kind;
 	prof->prof_id = dtrace_probe_create(profile_id,
 	    NULL, NULL, name,
-	    profile_aframes ? profile_aframes : PROF_ARTIFICIAL_FRAMES, prof);
+	    profile_aframes, prof);
 }
 
 /*ARGSUSED*/