Andrew,

On Wed, Sep 26, 2012 at 6:42 PM, Andrew Morton
[off-list ref] wrote:

On Tue, 25 Sep 2012 22:15:38 -0300
Ezequiel Garcia [off-list ref] wrote:

quoted

quoted

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.

I'll try that.

quoted

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.

I'm kind of lost. The patch really shouldn't fatten the kernel this way :-(

The patch was meant to improve tracing for memory tracking,
which in turn would be used to reduce memory footprint.
So, definitely I don't want to increase kernel text size.

I'll test that kernel config and see what I can do.

Thanks,
Ezequiel.

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