Don't send taskstats (per-pid or per-tgid) on thread exit when no one is
listening for such data.
Currently the taskstats interface allocates a structure, fills it in
and calls netlink to send out per-pid and per-tgid stats regardless of whether
a userspace listener for the data exists (netlink layer would check for that
and avoid the multicast).
As a result of this patch, the check for the no-listener case is performed
early, avoiding the redundant allocation and filling up of the taskstats
structures.
Signed-off-by: Balbir Singh <[email protected]>
Signed-off-by: Shailabh Nagar <[email protected]>
---
include/linux/taskstats_kern.h | 13 ++++++++++++-
1 files changed, 12 insertions(+), 1 deletion(-)
Index: linux-2.6.17/include/linux/taskstats_kern.h
===================================================================
--- linux-2.6.17.orig/include/linux/taskstats_kern.h 2006-06-26 16:45:33.000000000 -0400
+++ linux-2.6.17/include/linux/taskstats_kern.h 2006-06-26 16:47:08.000000000 -0400
@@ -9,6 +9,7 @@
#include <linux/taskstats.h>
#include <linux/sched.h>
+#include <net/genetlink.h>
enum {
TASKSTATS_MSG_UNICAST, /* send data only to requester */
@@ -19,9 +20,19 @@ enum {
extern kmem_cache_t *taskstats_cache;
extern struct mutex taskstats_exit_mutex;
+static inline int taskstats_has_listeners(void)
+{
+ if (!genl_sock)
+ return 0;
+ return netlink_has_listeners(genl_sock, TASKSTATS_LISTEN_GROUP);
+}
+
+
static inline void taskstats_exit_alloc(struct taskstats **ptidstats)
{
- *ptidstats = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
+ *ptidstats = NULL;
+ if (taskstats_has_listeners())
+ *ptidstats = kmem_cache_zalloc(taskstats_cache, SLAB_KERNEL);
}
static inline void taskstats_exit_free(struct taskstats *tidstats)
-
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