Date: Tue, 18 Aug 2015 17:09:41 +0300 From: Daniel Braniss <danny@cs.huji.ac.il> To: Hans Petter Selasky <hps@selasky.org> Cc: Rick Macklem <rmacklem@uoguelph.ca>, FreeBSD Net <freebsd-net@freebsd.org>, Slawa Olhovchenkov <slw@zxy.spb.ru>, FreeBSD stable <freebsd-stable@freebsd.org>, Christopher Forgeron <csforgeron@gmail.com> Subject: Re: ix(intel) vs mlxen(mellanox) 10Gb performance Message-ID: <47EC9292-082C-4801-B52F-4BD6B8310F99@cs.huji.ac.il> In-Reply-To: <55D333D6.5040102@selasky.org> References: <1D52028A-B39F-4F9B-BD38-CB1D73BF5D56@cs.huji.ac.il> <20150817094145.GB3158@zxy.spb.ru> <CAB2_NwBOLcL4EVjFN6=BvBC_YN=gmfZMweVbmb5ZPCsK4Hnx1g@mail.gmail.com> <17871443-E105-4434-80B1-6939306A865F@cs.huji.ac.il> <473274181.23263108.1439814072514.JavaMail.zimbra@uoguelph.ca> <7F892C70-9C04-4468-9514-EDBFE75CF2C6@cs.huji.ac.il> <805850043.24018217.1439848150695.JavaMail.zimbra@uoguelph.ca> <9D8B0503-E8FA-43CA-88F0-01F184F84D9B@cs.huji.ac.il> <1721122651.24481798.1439902381663.JavaMail.zimbra@uoguelph.ca> <55D333D6.5040102@selasky.org>
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sorry, it=E2=80=99s been a tough day, we had a major meltdown, caused by = a faulty gbic :-( anyways, could you tell me what to do? comment out, fix the off by one? the machine is not yet production. thanks, danny > On 18 Aug 2015, at 16:32, Hans Petter Selasky <hps@selasky.org> wrote: >=20 > On 08/18/15 14:53, Rick Macklem wrote: >> 2572 ifp->if_hw_tsomax =3D 65518; >>> >2573 ifp->if_hw_tsomaxsegcount =3D = IXGBE_82599_SCATTER; >>> >2574 ifp->if_hw_tsomaxsegsize =3D 2048; >=20 > Hi, >=20 > If IXGBE_82599_SCATTER is the maximum scatter/gather entries the = hardware can do, remember to subtract one fragment for the TCP/IP-header = mbuf! >=20 > I think there is an off-by-one here: >=20 > ifp->if_hw_tsomax =3D 65518; > ifp->if_hw_tsomaxsegcount =3D IXGBE_82599_SCATTER - 1; > ifp->if_hw_tsomaxsegsize =3D 2048; >=20 > Refer to: >=20 >> * >> * NOTE: The TSO limits only apply to the data payload part of >> * a TCP/IP packet. That means there is no need to subtract >> * space for ethernet-, vlan-, IP- or TCP- headers from the >> * TSO limits unless the hardware driver in question requires >> * so. >=20 > In sys/net/if_var.h >=20 > Thank you! >=20 > --HPS >=20
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