From: Stephen Hemminger <stephen@networkplumber.org>
To: Adrian Popescu <adriannnpopescu@gmail.com>
Cc: cake@lists.bufferbloat.net
Subject: Re: [Cake] Cake3 - source code and some questions
Date: Wed, 22 Apr 2015 17:45:25 -0700 [thread overview]
Message-ID: <20150422174525.50d964ea@urahara> (raw)
In-Reply-To: <CAF3M4P3sPri00uf2h5FfhbOf475xLZm7nM9SBMbKjNciaj3Dow@mail.gmail.com>
On Thu, 23 Apr 2015 00:02:35 +0300
Adrian Popescu <adriannnpopescu@gmail.com> wrote:
> e1000e (82574, dual port and quad port server e1000e adapters with
> various Intel chips) is exhibiting varying latency based on the used
> kernel.
>
> Local network ping latencies on Ubuntu 14.04 with its LTS 3.13 kernel
> are always below 0.5 milliseconds when idle and lightly loaded. The
> latest kernels from kernel.org are unable to match those latencies.
> These modern kernels are always seeing latencies of 2-3 milliseconds.
>
> Turning off all offloads on the involved ethernet e1000e network
> interfaces doesn't help. This is all physical Intel hardware with
> e1000e interfaces.
>
> Two idle hosts on a local network should be able to ping each other
> and get latencies which are always less than one millisecond. FreeBSD
> doesn't have this problem.
These NIC's have had a histrory of power management related issues.
I suspect some power management (maybe even in SMI) is turning off
parts of the chips and it is taking long to turn back on.
next prev parent reply other threads:[~2015-04-23 0:45 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-12 9:39 Adrian Popescu
2015-04-12 9:58 ` Jonathan Morton
2015-04-12 10:24 ` Jonathan Morton
2015-04-12 12:33 ` Adrian Popescu
2015-04-12 18:57 ` Jonathan Morton
2015-04-16 12:14 ` Adrian Popescu
2015-04-16 13:25 ` Jonathan Morton
2015-04-16 13:48 ` Adrian Popescu
2015-04-16 19:26 ` Dave Taht
2015-04-22 21:02 ` Adrian Popescu
2015-04-23 0:45 ` Stephen Hemminger [this message]
2015-04-23 9:01 ` Toke Høiland-Jørgensen
2015-04-23 10:56 ` Adrian Popescu
2015-04-23 11:01 ` Toke Høiland-Jørgensen
2015-04-23 11:05 ` Adrian Popescu
2015-04-23 11:09 ` Toke Høiland-Jørgensen
2015-04-23 11:13 ` Jonathan Morton
2015-04-16 13:49 ` Sebastian Moeller
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