bizarre em + TSO + MSS issue in RELENG_7
kip.macy at gmail.com
Sat Nov 17 15:19:48 PST 2007
On Nov 17, 2007 2:33 PM, Mike Andrews <mandrews at bit0.com> wrote:
> On Sat, 17 Nov 2007, Kip Macy wrote:
> > On Nov 17, 2007 10:33 AM, Denis Shaposhnikov <dsh at vlink.ru> wrote:
> >> On Sat, 17 Nov 2007 00:42:54 -0500 (EST)
> >> Mike Andrews <mandrews at 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...
Denis' tcpdump output doesn't show oversized segments, something else
appears to be happening there. Can you post your tcpdump output
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