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authorEric Dumazet <dada1@cosmosbay.com>2009-05-18 19:26:37 -0700
committerDavid S. Miller <davem@davemloft.net>2009-05-18 19:26:37 -0700
commit511e11e396dc596825ce04d53d7f6d579404bc01 (patch)
tree236f3316d5577d9a4abd9ee15d4479ac7ec113b0
parentc4ca2374312b4de819dd700e72a68395eddb5fcb (diff)
pkt_sched: gen_estimator: use 64 bit intermediate counters for bps
gen_estimator can overflow bps (bytes per second) with Gb links, while it was designed with a u32 API, with a theorical limit of 34360Mbit (2^32 bytes) Using 64 bit intermediate avbps/brate counters can allow us to reach this theorical limit. Signed-off-by: Eric Dumazet <dada1@cosmosbay.com> Signed-off-by: Jarek Poplawski <jarkao2@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--net/core/gen_estimator.c13
1 files changed, 7 insertions, 6 deletions
diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c
index 9cc9f95b109..6d62d4618cf 100644
--- a/net/core/gen_estimator.c
+++ b/net/core/gen_estimator.c
@@ -66,9 +66,9 @@
NOTES.
- * The stored value for avbps is scaled by 2^5, so that maximal
- rate is ~1Gbit, avpps is scaled by 2^10.
-
+ * avbps is scaled by 2^5, avpps is scaled by 2^10.
+ * both values are reported as 32 bit unsigned values. bps can
+ overflow for fast links : max speed being 34360Mbit/sec
* Minimal interval is HZ/4=250msec (it is the greatest common divisor
for HZ=100 and HZ=1024 8)), maximal interval
is (HZ*2^EST_MAX_INTERVAL)/4 = 8sec. Shorter intervals
@@ -86,9 +86,9 @@ struct gen_estimator
spinlock_t *stats_lock;
int ewma_log;
u64 last_bytes;
+ u64 avbps;
u32 last_packets;
u32 avpps;
- u32 avbps;
struct rcu_head e_rcu;
struct rb_node node;
};
@@ -115,6 +115,7 @@ static void est_timer(unsigned long arg)
rcu_read_lock();
list_for_each_entry_rcu(e, &elist[idx].list, list) {
u64 nbytes;
+ u64 brate;
u32 npackets;
u32 rate;
@@ -125,9 +126,9 @@ static void est_timer(unsigned long arg)
nbytes = e->bstats->bytes;
npackets = e->bstats->packets;
- rate = (nbytes - e->last_bytes)<<(7 - idx);
+ brate = (nbytes - e->last_bytes)<<(7 - idx);
e->last_bytes = nbytes;
- e->avbps += ((long)rate - (long)e->avbps) >> e->ewma_log;
+ e->avbps += ((s64)(brate - e->avbps)) >> e->ewma_log;
e->rate_est->bps = (e->avbps+0xF)>>5;
rate = (npackets - e->last_packets)<<(12 - idx);