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authorNeil Horman <nhorman@tuxdriver.com>2009-09-02 14:37:45 -0700
committerDavid S. Miller <davem@davemloft.net>2009-09-02 14:37:45 -0700
commit5848cc096a23b80b3d15c27d72299f79caf7c517 (patch)
treef43257578c3e5fc248903544c430294d914287a7 /net/core/drop_monitor.c
parent3f968de276a8e585deb182d4ba56013a479c80bc (diff)
net: drop_monitor: make last_rx timestamp private
It was recently pointed out to me that the last_rx field of the net_device structure wasn't updated regularly. In fact only the bonding driver really uses it currently. Since the drop_monitor code relies on the last_rx field to detect drops on recevie in hardware, We need to find a more reliable way to rate limit our drop checks (so that we don't check for drops on every frame recevied, which would be inefficient. This patch makes a last_rx timestamp that is private to the drop monitor code and is updated for every device that we track. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/drop_monitor.c')
-rw-r--r--net/core/drop_monitor.c15
1 files changed, 12 insertions, 3 deletions
diff --git a/net/core/drop_monitor.c b/net/core/drop_monitor.c
index d31120248c0..0a113f26bc9 100644
--- a/net/core/drop_monitor.c
+++ b/net/core/drop_monitor.c
@@ -52,6 +52,7 @@ struct per_cpu_dm_data {
struct dm_hw_stat_delta {
struct net_device *dev;
+ unsigned long last_rx;
struct list_head list;
struct rcu_head rcu;
unsigned long last_drop_val;
@@ -180,18 +181,25 @@ static void trace_napi_poll_hit(struct napi_struct *napi)
struct dm_hw_stat_delta *new_stat;
/*
- * Ratelimit our check time to dm_hw_check_delta jiffies
+ * Don't check napi structures with no associated device
*/
- if (!napi->dev ||
- !time_after(jiffies, napi->dev->last_rx + dm_hw_check_delta))
+ if (!napi->dev)
return;
rcu_read_lock();
list_for_each_entry_rcu(new_stat, &hw_stats_list, list) {
+ /*
+ * only add a note to our monitor buffer if:
+ * 1) this is the dev we received on
+ * 2) its after the last_rx delta
+ * 3) our rx_dropped count has gone up
+ */
if ((new_stat->dev == napi->dev) &&
+ (time_after(jiffies, new_stat->last_rx + dm_hw_check_delta)) &&
(napi->dev->stats.rx_dropped != new_stat->last_drop_val)) {
trace_drop_common(NULL, NULL);
new_stat->last_drop_val = napi->dev->stats.rx_dropped;
+ new_stat->last_rx = jiffies;
break;
}
}
@@ -287,6 +295,7 @@ static int dropmon_net_event(struct notifier_block *ev_block,
goto out;
new_stat->dev = dev;
+ new_stat->last_rx = jiffies;
INIT_RCU_HEAD(&new_stat->rcu);
spin_lock(&trace_state_lock);
list_add_rcu(&new_stat->list, &hw_stats_list);