> -----Original Message----- > From: Xinze Chi (信泽) [mailto:xmdx...@gmail.com] > Sent: Thursday, December 03, 2015 10:18 AM > To: Milosz Tanski > Cc: Sage Weil; Gregory Farnum; Dan Mick; Haomai Wang; Dałek, Piotr; ceph- > de...@vger.kernel.org > Subject: Re: ceph encoding optimization > > I write a new patch about this > https://github.com/XinzeChi/ceph/commit/06eb471e463a4687e251273d0b5 > dfe170acbef2d > > If you use __attribute__ ((packed)) after struct, we could encode many > struct member in a batch. There is not compatibility problem if we keep the > order of members defined in struct. > > Wait for your comment.
Fields in embedded structs might be aligned, that will inhibit packed attribute. Also, you can't just use packed attribute on every struct that is encoded/decoded because that will eventually incur a performance hit. What I had in mind with https://github.com/XinzeChi/ceph/commit/06eb471e463a4687e251273d0b5dfe170acbef2d#commitcomment-14755615 is to use temporary, packed struct, copy data from original struct/class into it, and then copy data from packed struct in one go. With best regards / Pozdrawiam Piotr Dałek
