From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: HTB accuracy for high speed Date: Sat, 16 May 2009 16:14:30 +0200 Message-ID: <20090516141430.GB3013@ami.dom.local> References: <298f5c050905150745p13dc226eia1ff50ffa8c4b300@mail.gmail.com> <298f5c050905150749s3597328dr8dd15adbd7a37532@mail.gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: netdev@vger.kernel.org, kaber@trash.net, davem@davemloft.net, devik@cdi.cz To: Antonio Almeida Return-path: Received: from mail-fx0-f158.google.com ([209.85.220.158]:59455 "EHLO mail-fx0-f158.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753755AbZEPOQK (ORCPT ); Sat, 16 May 2009 10:16:10 -0400 Received: by fxm2 with SMTP id 2so2416790fxm.37 for ; Sat, 16 May 2009 07:16:10 -0700 (PDT) Content-Disposition: inline In-Reply-To: <298f5c050905150749s3597328dr8dd15adbd7a37532@mail.gmail.com> Sender: netdev-owner@vger.kernel.org List-ID: On Fri, May 15, 2009 at 03:49:31PM +0100, Antonio Almeida wrote: =2E.. > I also note that, for HTB rate configurations over 500Mbit/s on leaf > class, when I stop the traffic, in the output of "tc -s -d class ls > dev eth1" command, I see that leaf's rate (in bits/s) is growing > instead of decreasing (as expected since I've stopped the traffic). > Rate in pps is ok and decreases until 0pps. Rate in bits/s increases > above 1000Mbit and stays there for a few minutes. After two or three > minutes it becomes 0bit. The same happens for it's ancestors (also fo= r > root class).Here's tc output of my leaf class for this situation: >=20 > class htb 1:108 parent 1:10 leaf 108: prio 7 quantum 1514 rate > 555000Kbit ceil 555000Kbit burst 70901b/8 mpu 0b overhead 0b cburst > 70901b/8 mpu 0b overhead 0b level 0 > =A0Sent 120267768144 bytes 242475339 pkt (dropped 62272599, overlimit= s 0 > requeues 0) > =A0rate 1074Mbit 0pps backlog 0b 0p requeues 0 > =A0lended: 242475339 borrowed: 0 giants: 0 > =A0tokens: 8 ctokens: 8 This looks like a regular bug. I guess it's an overflow in gen_estimator(), but I'm not sure there is nothing more. Could you try the patch below? (An offset warning when patching 2.6.25 is OK) Thanks, Jarek P. --- net/core/gen_estimator.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-) diff --git a/net/core/gen_estimator.c b/net/core/gen_estimator.c index 9cc9f95..87f0ced 100644 --- a/net/core/gen_estimator.c +++ b/net/core/gen_estimator.c @@ -127,7 +127,11 @@ static void est_timer(unsigned long arg) npackets =3D e->bstats->packets; rate =3D (nbytes - e->last_bytes)<<(7 - idx); e->last_bytes =3D nbytes; - e->avbps +=3D ((long)rate - (long)e->avbps) >> e->ewma_log; + if (rate > e->avbps) + e->avbps +=3D (rate - e->avbps) >> e->ewma_log; + else + e->avbps -=3D (e->avbps - rate) >> e->ewma_log; + e->rate_est->bps =3D (e->avbps+0xF)>>5; =20 rate =3D (npackets - e->last_packets)<<(12 - idx);