From a5ea18413ed6beb09aa13011f52cb7f193b1614e Mon Sep 17 00:00:00 2001
From: davidxu <davidxu@FreeBSD.org>
Date: Fri, 29 Oct 2010 13:31:10 +0000
Subject: Add sysctl kern.sched.cpusetsize to export the size of kernel cpuset,
 also add sysconf() key _SC_CPUSET_SIZE to get sysctl value.

Submitted by: gcooper
---
 include/unistd.h       |  1 +
 lib/libc/gen/sysconf.c |  9 +++++++++
 sys/kern/sched_ule.c   | 11 +++++++++++
 3 files changed, 21 insertions(+)

diff --git a/include/unistd.h b/include/unistd.h
index 4ae6917..34f187c 100644
--- a/include/unistd.h
+++ b/include/unistd.h
@@ -288,6 +288,7 @@ typedef	__useconds_t	useconds_t;
 #if __BSD_VISIBLE
 #define	_SC_NPROCESSORS_CONF	57
 #define	_SC_NPROCESSORS_ONLN	58
+#define	_SC_CPUSET_SIZE		122
 #endif
 
 /* Extensions found in Solaris and Linux. */
diff --git a/lib/libc/gen/sysconf.c b/lib/libc/gen/sysconf.c
index 4618f32..7539d61 100644
--- a/lib/libc/gen/sysconf.c
+++ b/lib/libc/gen/sysconf.c
@@ -597,6 +597,15 @@ yesno:
 		return (lvalue);
 #endif
 
+#ifdef _SC_CPUSET_SIZE
+	case _SC_CPUSET_SIZE:
+		len = sizeof(lvalue);
+		if (sysctlbyname("kern.sched.cpusetsize", &lvalue, &len, NULL,
+		    0) == -1)
+			return (-1);
+		return (lvalue);
+#endif
+
 	default:
 		errno = EINVAL;
 		return (-1);
diff --git a/sys/kern/sched_ule.c b/sys/kern/sched_ule.c
index 4765c1c..641979d 100644
--- a/sys/kern/sched_ule.c
+++ b/sys/kern/sched_ule.c
@@ -2712,6 +2712,8 @@ sysctl_kern_sched_topology_spec(SYSCTL_HANDLER_ARGS)
 	sbuf_delete(topo);
 	return (err);
 }
+
+static size_t _kern_cpuset_size = sizeof(cpuset_t);
 #endif
 
 SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RW, 0, "Scheduler");
@@ -2748,6 +2750,15 @@ SYSCTL_INT(_kern_sched, OID_AUTO, steal_thresh, CTLFLAG_RW, &steal_thresh, 0,
 SYSCTL_PROC(_kern_sched, OID_AUTO, topology_spec, CTLTYPE_STRING |
     CTLFLAG_RD, NULL, 0, sysctl_kern_sched_topology_spec, "A", 
     "XML dump of detected CPU topology");
+
+/* 
+ * Return the size of cpuset_t at the kernel level
+ *
+ * XXX (gcooper): replace ULONG with SIZE once CTLTYPE_SIZE is implemented.
+ */
+SYSCTL_ULONG(_kern_sched, OID_AUTO, cpusetsize, CTLFLAG_RD,
+    &_kern_cpuset_size, 0, "Kernel-level cpuset_t struct size");
+
 #endif
 
 /* ps compat.  All cpu percentages from ULE are weighted. */
-- 
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