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Date:      Mon, 25 Jan 2010 10:38:28 -0800
From:      Nick Rogers <ncrogers@gmail.com>
To:        pyunyh@gmail.com
Cc:        Jason Chambers <jchambers@ucla.edu>, "stable@freebsd.org" <stable@freebsd.org>, "jfvogel@gmail.com" <jfvogel@gmail.com>, Lars Eggert <lars.eggert@nokia.com>
Subject:   Re: em interface slow down on 8.0R
Message-ID:  <147432021001251038r69393ab3m1a797e58f9fa905a@mail.gmail.com>
In-Reply-To: <20100125182257.GG1187@michelle.cdnetworks.com>
References:  <20091201.102925.218343479.hrs@allbsd.org> <2a41acea0912021249w1aed8e83kf89ceb1e6041edaf@mail.gmail.com> <2a41acea0912021514r2d44dd33n4c364518d7fe1703@mail.gmail.com> <20091203.182931.129751456.hrs@allbsd.org> <4B43F6EE.3010308@ucla.edu> <147432021001242047k659a26d0s44b35164920aeb74@mail.gmail.com> <95D3CB82-BC44-491D-86E4-5CB82F89C0FC@nokia.com> <147432021001250825p202914a7ka5a2c1d28d96bac3@mail.gmail.com> <20100125182257.GG1187@michelle.cdnetworks.com>

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On Mon, Jan 25, 2010 at 10:22 AM, Pyun YongHyeon <pyunyh@gmail.com> wrote:

> On Mon, Jan 25, 2010 at 08:25:43AM -0800, Nick Rogers wrote:
> > I have not tried toying with any tcp sysctl. I'm not having performance
> > problems so much as the interface just stops working entirely, which I
> would
> > think has nothing to do with the TCP stack when layer 2 is not
> functioning?
> >
>
> I'm not sure you're seeing a checksum offload bug of em(4) but the
> bug is easily reproducible in VLAN environments. If the issue is
> gone when you disable TX checksum offloading, see kern/141843 for
> for more detailed information as well as fix.
>

Good to know, but I am having a similar problem on another em(4) interface
that has no VLAN interfaces.

>
> > I'll give it a shot if I can. For the moment I have had to switch to a
> > different (lower performance) network card to get things stable and I
> would
> > like to be aware of a more concrete driver fix in STABLE before switching
> > back my production machines.
> >
> > On Mon, Jan 25, 2010 at 6:25 AM, Lars Eggert <lars.eggert@nokia.com>
> wrote:
> >
> > > Hi,
> > >
> > > have you tried turning off TCP Segmentation Offloading
> (net.inet.tcp.tso
> > > sysctl)? That fixed performance issues with some em cards for me.
> > >
> > > Lars
> > >
> > >
>



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