Messages in this thread | | | Date | Wed, 26 Sep 2012 14:42:19 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 05/10] mm, util: Use dup_user to duplicate user memory |
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On Tue, 25 Sep 2012 22:15:38 -0300 Ezequiel Garcia <elezegarcia@gmail.com> wrote:
> > 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.
x86_64 allmodconfig with CONFIG_DEBUG_INFO=n, CONFIG_ENABLE_MUST_CHECK=n. gcc-4.4.4.
> 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?
Dunno - it could be a config thing.
> 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).
hm. Perhaps we could add an __always_inline_for_tracing. But that wouldn't help a lot - a CONFIG_TRACING_SUPPORT=y kernel would still be impacted even if the user is never using tracing.
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