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From: "Thomas Rosenstein" <thomas.rosenstein@creamfinance.com>
To: "Jesper Dangaard Brouer" <brouer@redhat.com>
Cc: "Thomas Rosenstein via Bloat" <bloat@lists.bufferbloat.net>
Subject: Re: [Bloat] Router congestion, slow ping/ack times with kernel 5.4.60
Date: Mon, 09 Nov 2020 15:33:46 +0100	[thread overview]
Message-ID: <27110D8E-77DF-4D10-A5EA-6430DBD55BC7@creamfinance.com> (raw)
In-Reply-To: <20201109124030.71216677@carbon>



On 9 Nov 2020, at 12:40, Jesper Dangaard Brouer wrote:

> On Mon, 09 Nov 2020 11:09:33 +0100
> "Thomas Rosenstein" <thomas.rosenstein@creamfinance.com> wrote:
>
>> On 9 Nov 2020, at 9:24, Jesper Dangaard Brouer wrote:
>>
>>> On Sat, 07 Nov 2020 14:00:04 +0100
>>> Thomas Rosenstein via Bloat <bloat@lists.bufferbloat.net> wrote:
>>>
>>>> Here's an extract from the ethtool https://pastebin.com/cabpWGFz 
>>>> just
>>>> in
>>>> case there's something hidden.
>>>
>>> Yes, there is something hiding in the data from ethtool_stats.pl[1]:
>>> (10G Mellanox Connect-X cards via 10G SPF+ DAC)
>>>
>>>  stat:            1 (          1) <= outbound_pci_stalled_wr_events 
>>> /sec
>>>  stat:    339731557 (339,731,557) <= rx_buffer_passed_thres_phy /sec
>>>
>>> I've not seen this counter 'rx_buffer_passed_thres_phy' before, 
>>> looking
>>> in the kernel driver code it is related to "rx_buffer_almost_full".
>>> The numbers per second is excessive (but it be related to a driver 
>>> bug
>>> as it ends up reading "high" -> rx_buffer_almost_full_high in the
>>> extended counters).

I have now tested with a new kernel 5.9.4 build made from 3.10 with make 
oldconfig and I noticed an interesting effect.

The first ca. 2 minutes the router behaves completely normal as with 
3.10, after that the ping times go crazy.

I have recorded this with ethtool, and also the ping times.

Ethtool: (13 MB)
https://drive.google.com/file/d/1Ojp64UUw0zKwrgF_CisZb3BCdidAJYZo/view?usp=sharing

The transfer first was doing around 50 - 70 MB/s then once the ping 
times go worse it dropped to ~12 MB/s.
ca. Line 74324 the transfer speed drops to 12 MB/s

Seems you are right about the rx_buffer_passed_thres_phy if you check 
just those lines they appear more often once the speed dropped.
Not sure if that's the cause or an effect of the underlying problem!

Pings:
https://drive.google.com/file/d/16phOxM5IFU6RAl4Ua4pRqMNuLYBc4RK7/view?usp=sharing

Pause frames were activated again after the restart.

(Here a link for rerefence for the ethtool variables: 
https://community.mellanox.com/s/article/understanding-mlx5-ethtool-counters)

  parent reply	other threads:[~2020-11-09 14:33 UTC|newest]

Thread overview: 47+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-11-04 15:23 Thomas Rosenstein
2020-11-04 16:10 ` Toke Høiland-Jørgensen
2020-11-04 16:24   ` Thomas Rosenstein
2020-11-05  0:10     ` Toke Høiland-Jørgensen
2020-11-05  8:48       ` Thomas Rosenstein
2020-11-05 11:21         ` Toke Høiland-Jørgensen
2020-11-05 12:22           ` Thomas Rosenstein
2020-11-05 12:38             ` Toke Høiland-Jørgensen
2020-11-05 12:41               ` Thomas Rosenstein
2020-11-05 12:47                 ` Toke Høiland-Jørgensen
2020-11-05 13:33             ` Jesper Dangaard Brouer
2020-11-06  8:48               ` Thomas Rosenstein
2020-11-06 10:53                 ` Jesper Dangaard Brouer
2020-11-06  9:18               ` Thomas Rosenstein
2020-11-06 11:18                 ` Jesper Dangaard Brouer
2020-11-06 11:37                   ` Thomas Rosenstein
2020-11-06 11:45                     ` Toke Høiland-Jørgensen
2020-11-06 12:01                       ` Thomas Rosenstein
2020-11-06 12:53                       ` Jesper Dangaard Brouer
2020-11-06 14:13                         ` Jesper Dangaard Brouer
2020-11-06 17:04                           ` Thomas Rosenstein
2020-11-06 20:19                             ` Jesper Dangaard Brouer
2020-11-07 12:37                               ` Thomas Rosenstein
2020-11-07 12:40                                 ` Jan Ceuleers
2020-11-07 12:43                                   ` Thomas Rosenstein
2020-11-07 13:00                                   ` Thomas Rosenstein
2020-11-09  8:24                                     ` Jesper Dangaard Brouer
2020-11-09 10:09                                       ` Thomas Rosenstein
2020-11-09 11:40                                         ` Jesper Dangaard Brouer
2020-11-09 11:51                                           ` Toke Høiland-Jørgensen
2020-11-09 12:25                                           ` Thomas Rosenstein
2020-11-09 14:33                                           ` Thomas Rosenstein [this message]
2020-11-12 10:05                                             ` Jesper Dangaard Brouer
2020-11-12 11:26                                               ` Thomas Rosenstein
2020-11-12 13:31                                                 ` Jesper Dangaard Brouer
2020-11-12 13:42                                                   ` Thomas Rosenstein
2020-11-12 15:42                                                     ` Jesper Dangaard Brouer
2020-11-13  6:31                                                       ` Thomas Rosenstein
2020-11-16 11:56                                                         ` Jesper Dangaard Brouer
2020-11-16 12:05                                                           ` Thomas Rosenstein
2020-11-09 16:39                                           ` Thomas Rosenstein
2020-11-07 13:33                                 ` Thomas Rosenstein
2020-11-07 16:46                                 ` Jesper Dangaard Brouer
2020-11-07 17:01                                   ` Thomas Rosenstein
2020-11-07 17:26                                     ` Sebastian Moeller
2020-11-16 12:34 ` Jesper Dangaard Brouer
2020-11-16 12:49   ` Thomas Rosenstein

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