* Maksym Planeta <mcsim.planeta@xxxxxxxxx> wrote: > On Sat, 27/03/2011 at 13:33 +0200, Ingo Molnar wrote: > > Just wondering, what's the before/after 'size vmlinux' effect on a 'make > > defconfig' x86 kernel? Does the optimization make the kernel smaller as well, > > besides making it faster? > > Thank you for advice. I didn't really mentioned it. So without my patch: > > size vmlinux > text data bss dec hex filename > 7915025 1253060 1122304 10290389 9d04d5 vmlinux > > And with it: > > size vmlinux > text data bss dec hex filename > 7919150 1251364 1122304 10292818 9d0e52 vmlinux > > Size increased. But I discovered that if I replace "inline" with > "__always_inline" in get_order(), size will be following: > > size vmlinux > text data bss dec hex filename > 7914481 1249252 1122304 10286037 9cf3d5 vmlinux > > And this is less than with same modification in asm-general: > > size vmlinux > text data bss dec hex filename > 7914713 1249268 1122304 10286285 9cf4cd vmlinux > > With my patch and "__always_inline" instead of just "inline" size will > be the smallest. Weird, that's an unexpected resut. Have you looked at the disassembly, why does the size increase? I'd expect such a straight assembly optimization to result in smaller code: in the non-constant case it should be the same size as before, in the constant case it should be smaller, because BSR should be smaller than an open-coded search loop, right? One sidenote, defconfig turns these on: CONFIG_CC_OPTIMIZE_FOR_SIZE=y CONFIG_OPTIMIZE_INLINING=y And some versions of GCC arent very good with these. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
