Date: Tue, 18 Aug 2015 15:32:06 +0200 From: Hans Petter Selasky <hps@selasky.org> To: Rick Macklem <rmacklem@uoguelph.ca>, Daniel Braniss <danny@cs.huji.ac.il> Cc: 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: <55D333D6.5040102@selasky.org> In-Reply-To: <1721122651.24481798.1439902381663.JavaMail.zimbra@uoguelph.ca> 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>
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On 08/18/15 14:53, Rick Macklem wrote: > 2572 ifp->if_hw_tsomax = 65518; >> >2573 ifp->if_hw_tsomaxsegcount = IXGBE_82599_SCATTER; >> >2574 ifp->if_hw_tsomaxsegsize = 2048; Hi, 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! I think there is an off-by-one here: ifp->if_hw_tsomax = 65518; ifp->if_hw_tsomaxsegcount = IXGBE_82599_SCATTER - 1; ifp->if_hw_tsomaxsegsize = 2048; Refer to: > * > * 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. In sys/net/if_var.h Thank you! --HPS
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