Adrian Bunk a écrit :
On Sun, Dec 16, 2007 at 06:42:57PM +0100, Eric Dumazet wrote:
Adrian Bunk a écrit :
...
And even more funny, with gcc 4.2 and CONFIG_CC_OPTIMIZE_FOR_SIZE=y your
patch doesn't seem to make any space difference - are you using an older
compiler or even worse CONFIG_CC_OPTIMIZE_FOR_SIZE=n for being able to see
any space difference?
In both cases your code uglification would be even more pointless...
I believe that CONFIG_SMP is uglification for you Adrian, but still I am
glad linux have it.
If your CONFIG_SYSCTL=n is really that important for you, why dont you
define a new qualifier that can indeed mark some variables as :
const if CONFIG_SYSCTL=n
read_mostly if CONFIG_SYCTL=y
This way you can keep compiler optimizations for your CONFIG_SYCTL=n, while
many people like me can still continue to optimize their kernel.
Seeing so many sysctl already read_mostly in kernel, I wonder why you NACK
my patch, while it's easy to share your concerns with other people and find
a solution.
You omitted an answer to my main important point...
Let me ask it in a more simple way:
Do you see any space difference at all with gcc 4.2 and
CONFIG_CC_OPTIMIZE_FOR_SIZE=y ?
I am using gcc-4.2.1
CONFIG_CC_OPTIMIZE_FOR_SIZE=y makes no difference for me.
$ make defconfig
$ egrep "OPTIMIZE_FOR_SIZE|CONFIG_SMP" .config
CONFIG_CC_OPTIMIZE_FOR_SIZE=y
CONFIG_SMP=y
$ make vmlinux
$ nm -v vmlinux|grep -4 random_read_wakeup_thresh
c057a02c d excluded_id_list
c057a100 d zero_bdi
c057a180 D random_table
c057a300 d input_pool
c057a400 d random_read_wakeup_thresh
c057a404 d random_write_wakeup_thresh
<SAME HOLE HERE>
c057a480 d blocking_pool
c057a580 d nonblocking_pool
c057a680 d rekey_work
After my patch, I still gain 120 bytes.
Please realize that most people now build their kernels with CONFIG_SMP=y, or
use a distro one (with CONFIG_SMP=y as well)
Your CONFIG_SYSCTL point is valid and should be addressed by a separate patch set.
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