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[net,4/4] openvswitch: Correctly report flow used times for first 5 minutes after boot.

Message ID 1395338954-26206-5-git-send-email-jesse@nicira.com
State Accepted, archived
Delegated to: David Miller
Headers show

Commit Message

Jesse Gross March 20, 2014, 6:09 p.m. UTC 
From: Ben Pfaff <blp@nicira.com>

The kernel starts out its "jiffies" timer as 5 minutes below zero, as
shown in include/linux/jiffies.h:

  /*
   * Have the 32 bit jiffies value wrap 5 minutes after boot
   * so jiffies wrap bugs show up earlier.
   */
  #define INITIAL_JIFFIES ((unsigned long)(unsigned int) (-300*HZ))

The loop in ovs_flow_stats_get() starts out with 'used' set to 0, then
takes any "later" time.  This means that for the first five minutes after
boot, flows will always be reported as never used, since 0 is greater than
any time already seen.

Signed-off-by: Ben Pfaff <blp@nicira.com>
Acked-by: Pravin B Shelar <pshelar@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
---
 net/openvswitch/flow.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox

Patch

diff --git a/net/openvswitch/flow.c b/net/openvswitch/flow.c
index d71e60f..dda451f 100644
--- a/net/openvswitch/flow.c
+++ b/net/openvswitch/flow.c
@@ -92,7 +92,7 @@  static void stats_read(struct flow_stats *stats,
 		       unsigned long *used, __be16 *tcp_flags)
 {
 	spin_lock(&stats->lock);
-	if (time_after(stats->used, *used))
+	if (!*used || time_after(stats->used, *used))
 		*used = stats->used;
 	*tcp_flags |= stats->tcp_flags;
 	ovs_stats->n_packets += stats->packet_count;