Patch "net_sched: gen_estimator: fix scaling error in bytes/packets samples" has been added to the 4.13-stable tree

Patch "net_sched: gen_estimator: fix scaling error in bytes/packets samples" has been added to the 4.13-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

    net_sched: gen_estimator: fix scaling error in bytes/packets samples

to the 4.13-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net_sched-gen_estimator-fix-scaling-error-in-bytes-packets-samples.patch
and it can be found in the queue-4.13 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From foo@baz Mon Oct  9 09:32:35 CEST 2017
From: Eric Dumazet <edumazet@google.com>
Date: Wed, 13 Sep 2017 11:16:45 -0700
Subject: net_sched: gen_estimator: fix scaling error in bytes/packets samples

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);


Patches currently in stable-queue which might be from edumazet@google.com are

queue-4.13/packet-in-packet_do_bind-test-fanout-with-bind_lock-held.patch
queue-4.13/socket-bpf-fix-possible-use-after-free.patch
queue-4.13/bpf-do-not-disable-enable-bh-in-bpf_map_free_id.patch
queue-4.13/packet-only-test-po-has_vnet_hdr-once-in-packet_snd.patch
queue-4.13/8139too-revisit-napi_complete_done-usage.patch
queue-4.13/net_sched-gen_estimator-fix-scaling-error-in-bytes-packets-samples.patch
queue-4.13/tcp-fastopen-fix-on-syn-data-transmit-failure.patch
queue-4.13/bpf-fix-bpf_tail_call-x64-jit.patch
queue-4.13/net-set-sk_prot_creator-when-cloning-sockets-to-the-right-proto.patch
queue-4.13/tcp-fix-data-delivery-rate.patch