Hi Andrew, On Tue, Sep 25, 2012 at 6:29 PM, Andrew Morton <a...@linux-foundation.org> wrote: > On Sat, 8 Sep 2012 17:47:54 -0300 > Ezequiel Garcia <elezegar...@gmail.com> wrote: > >> Previously the strndup_user allocation was being done through memdup_user, >> and the caller was wrongly traced as being strndup_user >> (the correct trace must report the caller of strndup_user). >> >> This is a common problem: in order to get accurate callsite tracing, >> a utils function can't allocate through another utils function, >> but instead do the allocation himself (or inlined). >> >> Here we fix this by creating an always inlined dup_user() function to >> performed the real allocation and to be used by memdup_user and strndup_user. > > This patch increases util.o's text size by 238 bytes. A larger kernel > with a worsened cache footprint. > > And we did this to get marginally improved tracing output? This sounds > like a bad tradeoff to me. >
Mmm, that's bad tradeoff indeed. It's certainly odd since the patch shouldn't increase the text size *that* much. Is it too much to ask that you send your kernel config and gcc version. My compilation (x86 kernel in gcc 4.7.1) shows a kernel less bloated: $ readelf -s util-dup-user.o | grep dup_user 161: 00001c10 108 FUNC GLOBAL DEFAULT 1 memdup_user 169: 00001df0 159 FUNC GLOBAL DEFAULT 1 strndup_user $ readelf -s util.o | grep dup_user 161: 00001c10 108 FUNC GLOBAL DEFAULT 1 memdup_user 169: 00001df0 98 FUNC GLOBAL DEFAULT 1 strndup_user $ size util.o text data bss dec hex filename 18319 2077 0 20396 4fac util.o $ size util-dup-user.o text data bss dec hex filename 18367 2077 0 20444 4fdc util-dup-user.o Am I doing anything wrong? If you still feel this is unnecessary bloatness, perhaps I could think of something depending on CONFIG_TRACING (though I know we all hate those nasty ifdefs). Anyway, thanks for the review, Ezequiel. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
