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Date:      Sat, 17 Nov 2007 17:33:14 -0500 (EST)
From:      Mike Andrews <mandrews@bit0.com>
To:        Kip Macy <kip.macy@gmail.com>
Cc:        Denis Shaposhnikov <dsh@vlink.ru>, Mike Silbersack <silby@freebsd.org>, Andre Oppermann <andre@freebsd.org>, freebsd-current@freebsd.org
Subject:   Re: bizarre em + TSO + MSS issue in RELENG_7
Message-ID:  <20071117170537.F59492@mindcrime.int.bit0.com>
In-Reply-To: <b1fa29170711171308x62a6371dnbb939748c5c59ae2@mail.gmail.com>
References:  <20071117003504.R31357@mindcrime.int.bit0.com> <20071117213316.499be43b@vlink.ru> <b1fa29170711171308x62a6371dnbb939748c5c59ae2@mail.gmail.com>

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On Sat, 17 Nov 2007, Kip Macy wrote:

> On Nov 17, 2007 10:33 AM, Denis Shaposhnikov <dsh@vlink.ru> wrote:
>> On Sat, 17 Nov 2007 00:42:54 -0500 (EST)
>> Mike Andrews <mandrews@bit0.com> wrote:
>>
>>> Has anyone run into problems with MSS not being respected when using
>>> TSO, specifically on em cards?
>>
>> Yes, I wrote about this problem on the beginning of 2007, see
>>
>>     http://tinyurl.com/3e5ak5
>>
>
> if_em.c:3502
>        /*
>         * Payload size per packet w/o any headers.
>         * Length of all headers up to payload.
>         */
>        TXD->tcp_seg_setup.fields.mss = htole16(mp->m_pkthdr.tso_segsz);
>        TXD->tcp_seg_setup.fields.hdr_len = hdr_len;
>
>
> Please print out the value of tso_segsz here. It appears to be being
> set correctly. The only thing I can think of is that t_maxopd is not
> correct. As tso_segsz is correct here:


It repeatedly prints 1368 during a 1 meg file transfer over a connection 
with a 1380 MSS.  Any other printf's I can add?  I'm working on a web page 
with tcpdump / firewall log output illustrating the issue...





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