On Thu, 5 Nov 2009, Noah Watkins wrote: > Sage > > A large number of le32_to_cpu (and the like) are used throughout the kernel > client when referencing packed structs that are used OTW. However, I'd argue > conversion should be done in only two places: before being sent or received. > This allows non-packed versions of structs to be used only on the local > machine, and use optimized alignment determined by gcc. Additionally it > de-clutters the code of all the conversion routines. The patch I attached (not > ready for use) demonstrates this for struct ceph_file_layout by introducing > struct __ceph_file_layout for OTW, and does conversion only before sending or > receiving over the network. > > Comments, suggestions?
With the caveat that the performance advantages here are pretty minimal (most users are little endian, struct is i think already aligned), this does clean things up a bit. I wouldn't change the types ceph_fs.[ch], msgr.h, rados.h if you can... these are all OTW types and shared between kernel and user space. Maybe make __ceph_file_layout the internal type. Maybe lose the fl_ prefix to catch accidental misuse. Are there other types you were looking at? I think most others are in the decode/use once category anyway? sage ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july _______________________________________________ Ceph-devel mailing list Ceph-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/ceph-devel
