On Tue, Jul 19, 2016 at 10:52:08AM +0200, Christoph Hellwig wrote: > > On Mon, Jul 18, 2016 at 03:37:46PM +1000, Dave Chinner wrote: > > > The reason I did this in the first place was a vague notion that unconditional > > > packing was harmful. > > > > > > http://digitalvampire.org/blog/index.php/2006/07/31/why-you-shouldnt-use-__attribute__packed/ > > > > > > "However, it's actively harmful to add the attribute to a structure that's > > > already going to be laid out with no padding." > > > ... > > > "gcc gets scared about unaligned accesses and generates six times as much code > > > (96 bytes vs. 16 bytes)! sparc64 goes similarly crazy, bloating from 12 bytes > > > to 52 bytes" > > > > > > I don't know if that's (still) correct or not, but that was the reason > > > for the selective __pack application way back when. Might be worth > > > investigating? > > > > Christoph? The first two ptches are fine, but more info is needed > > for this one... > > I don't have a sparc64 compiler to test unfortunately. But I can confirm > that on x86-64 xfs.o is bit to bit identical with or without the patch. OK, that's probably good enough to go with for now. Thanks for following up, Christoph. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
