| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.13 008/160] net_sched: gen_estimator: fix scaling error in bytes/packets samples | Date | Tue, 10 Oct 2017 21:48:56 +0200 |
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4.13-stable review patch. If anyone has any objections, please let me know.
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From: Eric Dumazet <edumazet@google.com>
[ Upstream commit ca558e185972d8ecd308760abf972f5d408bcff0 ]
Denys reported wrong rate estimations with HTB classes.
It appears the bug was added in linux-4.10, since my tests where using intervals of one second only.
HTB using 4 sec default rate estimators, reported rates were 4x higher.
We need to properly scale the bytes/packets samples before integrating them in EWMA.
Tested: echo 1 >/sys/module/sch_htb/parameters/htb_rate_est
Setup HTB with one class with a rate/cail of 5Gbit
Generate traffic on this class
tc -s -d cl sh dev eth0 classid 7002:11 class htb 7002:11 parent 7002:1 prio 5 quantum 200000 rate 5Gbit ceil 5Gbit linklayer ethernet burst 80000b/1 mpu 0b cburst 80000b/1 mpu 0b level 0 rate_handle 1 Sent 1488215421648 bytes 982969243 pkt (dropped 0, overlimits 0 requeues 0) rate 5Gbit 412814pps backlog 136260b 2p requeues 0 TCP pkts/rtx 982969327/45 bytes 1488215557414/68130 lended: 22732826 borrowed: 0 giants: 0 tokens: -1684 ctokens: -1684
Fixes: 1c0d32fde5bd ("net_sched: gen_estimator: complete rewrite of rate estimators") Signed-off-by: Eric Dumazet <edumazet@google.com> Reported-by: Denys Fedoryshchenko <nuclearcat@nuclearcat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- net/core/gen_estimator.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/net/core/gen_estimator.c +++ b/net/core/gen_estimator.c @@ -83,10 +83,10 @@ static void est_timer(unsigned long arg) u64 rate, brate; est_fetch_counters(est, &b); - brate = (b.bytes - est->last_bytes) << (8 - est->ewma_log); + brate = (b.bytes - est->last_bytes) << (10 - est->ewma_log - est->intvl_log); brate -= (est->avbps >> est->ewma_log); - rate = (u64)(b.packets - est->last_packets) << (8 - est->ewma_log); + rate = (u64)(b.packets - est->last_packets) << (10 - est->ewma_log - est->intvl_log); rate -= (est->avpps >> est->ewma_log); write_seqcount_begin(&est->seq);
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