On Wed, 21 Dec 2011 17:33:23 -0500 Peter Staubach <pstaubach@xxxxxxxxxxx> wrote: > I will need to disagree with the assertion regarding XDR and the packed struct. XDR can handle a versioned struct very neatly. It can do so just as easily as text string parsing and with greatly reduced overhead. > Ok, I'll bite -- what does XDR give us in this situation over a packed struct? Clearly there are benefits when the producer and consumer may have considerable differences, as is the case between networked hosts. For instance, different endianness or word size, etc. Here though, the producer and consumer are the same host, so we can be reasonably sure that the endianness is the same. I made sure to define the struct with explicit sizes for the fields, so word size isn't a factor. There's also a version field at the head so we could potentially rev the upcall struct version later if needed. An XDR format would need the same thing... AFAICS, Using XDR is just going to add extra overhead here, but not eliminate any of the drawbacks. If we have to rev the format later, we'll be in the same situation. A text based upcall has similar issues too, but it does at least make debugging simpler. As Chuck points out too, there is some variability in arguments as well. I think too that we're going to end up adding some other upcalls here, and those will also need a different set of arguments from what's there today. -- Jeff Layton <jlayton@xxxxxxxxxx> -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
