On Thu, Sep 1, 2016 at 4:04 PM, matthew green <m...@eterna.com.au> wrote: > have you tested other values than 1 and 16? what about 4 or 8?
4 and 8 are not so good; their performance fluctuations are similar to the unaligned case in my experiments. > > can you post the size difference of kernels? particularly the > kernel without DIAGNOSTIC or DEBUG (since those are the ones > where performance matters most.) I measured the sizes of GENERIC kernels, i.e., DIAGNOSTIC on and DEBUG off. The sizes of kernel binaries don't change in most cases because the alignment of __rodata_start that begins just after kernel text hides the changes due to -falign-functions. The sizes of the actual kernel text (from kernel_text to _etext) slightly changes. The difference between that of GENERIC kernels w/ and w/o -falign-functions=16 is 200kB. That is 1% of the total kernel text size. BTW, as I noted, I'm not exploring an alignment size that provides best performance, I just want to reduce performance fluctuations. Thanks, ozaki-r