Date: Sat, 17 Nov 2007 16:19:25 -0800 From: "Kip Macy" <kip.macy@gmail.com> To: "Mike Andrews" <mandrews@bit0.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: <b1fa29170711171619x24233a3cw4361e0f3ca395e4c@mail.gmail.com> In-Reply-To: <20071117182232.T59492@mindcrime.int.bit0.com> References: <20071117003504.R31357@mindcrime.int.bit0.com> <20071117213316.499be43b@vlink.ru> <b1fa29170711171308x62a6371dnbb939748c5c59ae2@mail.gmail.com> <20071117170537.F59492@mindcrime.int.bit0.com> <b1fa29170711171519r65473426s1b9f3d9666ff6a92@mail.gmail.com> <20071117182232.T59492@mindcrime.int.bit0.com>
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On Nov 17, 2007 3:23 PM, Mike Andrews <mandrews@bit0.com> wrote: > > On Sat, 17 Nov 2007, Kip Macy wrote: > > > On Nov 17, 2007 2:33 PM, Mike Andrews <mandrews@bit0.com> wrote: > >> 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... > > > > Mike - > > Denis' tcpdump output doesn't show oversized segments, something else > > appears to be happening there. Can you post your tcpdump output > > somewhere? > > > URL sent off-list. if (tso) { m->m_pkthdr.csum_flags = CSUM_TSO; m->m_pkthdr.tso_segsz = tp->t_maxopd - optlen; } Please print the value of maxopd and optlen under "if (tso)" in tcp_output. I think the calculated optlen may be too small. -Kip
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