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pkt_sched: gen_estimator: use 64 bit intermediate counters for bps

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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>
This commit is contained in:
Eric Dumazet 2009-05-18 19:26:37 -07:00 committed by David S. Miller
parent c4ca237431
commit 511e11e396
1 changed files with 7 additions and 6 deletions
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13
net/core/gen_estimator.c
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@ -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);