Date: Thu, 18 Sep 2014 16:16:34 +0200 From: Stefano Garzarella <stefanogarzarella@gmail.com> To: Hans Petter Selasky <hps@selasky.org> Cc: "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>, Adrian Chadd <adrian@freebsd.org>, freebsd-current <freebsd-current@freebsd.org>, Luigi Rizzo <rizzo@iet.unipi.it>, George Neville-Neil <gnn@neville-neil.com> Subject: Re: [RFC] Patch to add Software/Generic Segmentation Offload (GSO) support in FreeBSD Message-ID: <CAO0mX5ZGGY5fMmc%2BTFrknFrGrErrB7fx=f%2BSDMRg7oTTVHTRVg@mail.gmail.com> In-Reply-To: <5419EE95.40600@selasky.org> References: <CAO0mX5bDoCe8oRNmd%2BUBbr4bJcgQEzhAQKyTsyxEQciyvGTdgQ@mail.gmail.com> <CAJ-VmomY7M2h2Bbuu5BXRUYFRMnKXezZfCNbNWGFHACuFwNDmg@mail.gmail.com> <CAO0mX5Zdt487=entnjrMjxpt%2BLhKTNkS=sUHsnyVDYr_PXyS7Q@mail.gmail.com> <5419EE95.40600@selasky.org>
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Hi Hans, I saw the discussion about TSO, but the GSO is a software implementation unrelated with the hardware. Furthermore, if the TSO is enabled (and supported by the NIC), the GSO is not executed, because is useless. After the execution of the GSO, the packets, that are passed to the device driver, are smaller (or equal) than MTU, so the TSO is unnecessary. For this reason the GSO doesn't look neither "ifp->if_hw_tsomax" nor hardware segment limits. The GSO is very useful when you can't use the TSO. Cheers, Stefano 2014-09-17 22:27 GMT+02:00 Hans Petter Selasky <hps@selasky.org>: > On 09/17/14 20:18, Stefano Garzarella wrote: > >> Hi Adrian, >> the results that I sent, regard just one flow, but I can try with two >> simultaneous flows and I'll send you the results. >> >> Thanks, >> Stefano >> >> > Hi Stefano, > > You might have seen the discussion about TSO. Is it so that the proposed > GSO feature only looks at the "ifp->if_hw_tsomax" field, and ignores > hardware limits regarding maximum segment size and maximum segment count? > > --HPS > -- *Stefano Garzarella* stefano.garzarella@gmail.com
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