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| author | Eric Dumazet <dada1@cosmosbay.com> | 2009-05-18 19:26:37 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2009-05-18 19:26:37 -0700 |
| commit | 511e11e396dc596825ce04d53d7f6d579404bc01 (patch) | |
| tree | 236f3316d5577d9a4abd9ee15d4479ac7ec113b0 | |
| parent | c4ca2374312b4de819dd700e72a68395eddb5fcb (diff) | |
| download | linux-3.10-511e11e396dc596825ce04d53d7f6d579404bc01.tar.gz linux-3.10-511e11e396dc596825ce04d53d7f6d579404bc01.tar.bz2 linux-3.10-511e11e396dc596825ce04d53d7f6d579404bc01.zip | |
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.c | 13 |
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); |