On Wed, 5 Sep 2007, Michael S. Tsirkin wrote:
> > Quoting James Lentini <[EMAIL PROTECTED]>: > > Subject: Re: [PATCHv2] IB/ipoib: S/G and HW checksum support > > > > > > > > On Tue, 4 Sep 2007, Michael S. Tsirkin wrote: > > > > > > Quoting James Lentini <[EMAIL PROTECTED]>: > > > > Subject: Re: [PATCHv2] IB/ipoib: S/G and HW checksum support > > > > > > > > > > > > > > > > On Tue, 4 Sep 2007, Michael S. Tsirkin wrote: > > > > > > > > > Add module option hw_csum: when set, IPoIB will report S/G > > > > > support, and rely on hardware end-to-end transport checksum (ICRC) > > > > > instead of software-level protocol checksums. > > > > > > > > The purpose of this option would be clearer if the parameter name were > > > > "omit_csum". Calling this "HW checksum" support is misleading because > > > > the term is already used to describe network adapters that calculate > > > > TCP/IP checksums in hardware. I realize that you are using the HW > > > > checksum infrastructure to implement this, but it is really not the > > > > same thing. > > > > > > Another reason is that I declare HW_CSUM in the netdev > > > feature list. Yea, someone might get confused, > > > but "omit checksum" is misleading, too, and is likely to > > > scare users away from the feature: the need for end-to-end checksum > > > is a widely recognised requirement. > > > > I agree. Since this isn't an end-to-end checksum, > > IB spec says: <snip> > So yes, ICRC is an end-to-end checksum. This is made clear in the > modinfo description of the parameter. The ICRC checksum is a fine checksum. Your defining end-to-end as one end of an IB network to another. End-to-end in Internet terms is from one host to another over many potential networks. The source of a TCP packet could be on a IB network and be communicating with a node across the globe on a token ring. The TCP checksum is from source to destination, end-to-end. If you don't perform the TCP checksum at the source, there is no end-to-end checksum. > > I recommend that be made clear to the user. > > I don't think there's any potential for confusion There is a potential for confusion. The threads on this topic show that. How about naming the module parameter "omit_inet_csums"? > > > So I don't have a better name. Hopefully modinfo documents the > > > option well enough. > > > > > > > > Since this will not inter-operate with older IPoIB modules, this > > > > > option is off by default. > > > > > > > > > > Signed-off-by: Michael S. Tsirkin <[EMAIL PROTECTED]> > > > > > > > > Does the S/G support need to be tied to the checksum changes? > > > > Can you separate the S/G support and checksum changes into different > > patches? > > Oh, just cut the relevant hunks from the patch, but I don't see why > this is useful, since S/G support in linux does not work without > hardware checksumming. Ok. Given that, there's no reason to separate them. _______________________________________________ general mailing list [email protected] http://lists.openfabrics.org/cgi-bin/mailman/listinfo/general To unsubscribe, please visit http://openib.org/mailman/listinfo/openib-general
