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>

diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c
index 9cc9f95b109e72abaa5135d99cd0665d889415fa..6d62d4618cfc66a5c106e331b3eca0e85ff41f28 100644 (file)
--- 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);