Messages in this thread | | | Date | Fri, 13 Sep 2019 07:42:15 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v3 6/6] x86: bug.h: use asm_inline in _BUG_FLAGS definitions |
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* Rasmus Villemoes <linux@rasmusvillemoes.dk> wrote:
> This helps preventing a BUG* or WARN* in some static inline from > preventing that (or one of its callers) being inlined, so should allow > gcc to make better informed inlining decisions. > > For example, with gcc 9.2, tcp_fastopen_no_cookie() vanishes from > net/ipv4/tcp_fastopen.o. It does not itself have any BUG or WARN, but > it calls dst_metric() which has a WARN_ON_ONCE - and despite that > WARN_ON_ONCE vanishing since the condition is compile-time false, > dst_metric() is apparently sufficiently "large" that when it gets > inlined into tcp_fastopen_no_cookie(), the latter becomes too large > for inlining. > > Overall, if one asks size(1), .text decreases a little and .data > increases by about the same amount (x86-64 defconfig) > > $ size vmlinux.{before,after} > text data bss dec hex filename > 19709726 5202600 1630280 26542606 195020e vmlinux.before > 19709330 5203068 1630280 26542678 1950256 vmlinux.after > > while bloat-o-meter says > > add/remove: 10/28 grow/shrink: 103/51 up/down: 3669/-2854 (815) > ... > Total: Before=14783683, After=14784498, chg +0.01% > > Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Acked-by: Ingo Molnar <mingo@kernel.org>
Thanks,
Ingo
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