XFS binary code size

XFS binary code size

[Stan Hoeppner]

I'm curious about the footprint of the XFS binary code, specifically for 
32 bit systems, but knowing the 64 bit case would be educational as well 
for comparison.  I don't use kernel modules or I'd already have a rough 
answer.  My last build was 2.6.38.6 but I'm sure the size hasn't changed 
much in more recent kernels.  My XFS build options were:

$ grep -i xfs .config
CONFIG_XFS_FS=y
# CONFIG_XFS_QUOTA is not set
# CONFIG_XFS_POSIX_ACL is not set
# CONFIG_XFS_RT is not set

My resulting kernel image is:
$ la /boot/vmlinuz-2.6.38.6
-rw-r--r--  1 root root 1.6M May 17 23:55 vmlinuz-2.6.38.6

How much of that 1.6MB is XFS?  Also, what is the size of the hot path 
code that we want to stay in L1 during heavy IO?

-- 
Stan

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs

Re: XFS binary code size

[Dave Chinner]

On Mon, Sep 26, 2011 at 06:12:45PM -0500, Stan Hoeppner wrote:
> I'm curious about the footprint of the XFS binary code, specifically
> for 32 bit systems, but knowing the 64 bit case would be educational
> as well for comparison.  I don't use kernel modules or I'd already
> have a rough answer.  My last build was 2.6.38.6 but I'm sure the
> size hasn't changed much in more recent kernels.  My XFS build
> options were:
> 
> $ grep -i xfs .config
> CONFIG_XFS_FS=y
> # CONFIG_XFS_QUOTA is not set
> # CONFIG_XFS_POSIX_ACL is not set
> # CONFIG_XFS_RT is not set
> 
> My resulting kernel image is:
> $ la /boot/vmlinuz-2.6.38.6
> -rw-r--r--  1 root root 1.6M May 17 23:55 vmlinuz-2.6.38.6
> 
> How much of that 1.6MB is XFS?

That's the compressed image that is 1.6MB, so the uncompressed
kernel will be quite a bit bigger than that. As it is, the XFs
binary size can be found from your source tree via:

$ size fs/xfs/xfs.ko
   text    data     bss     dec     hex filename
 468288   59632    1400  529320   813a8 fs/xfs/xfs.ko
$

So for my current kernel build on x86-64 with these options:

CONFIG_XFS_FS=y
CONFIG_XFS_QUOTA=y
CONFIG_XFS_POSIX_ACL=y
CONFIG_XFS_RT=y
# CONFIG_XFS_DEBUG is not set

the XFS binary footprint is around 520kB. Yours will be smaller
given you don't have RT, ACL and quota configured, but it will still
probably be the largest single code block in your kernel...

> Also, what is the size of the hot
> path code that we want to stay in L1 during heavy IO?

Simple answer: it will stay in the L2 cache if we are lucky and
userspace doesn't trash the L2 cache between syscalls.

More complex answer: run perf w/ sampling on L1/L2 cache misses and
have a look for yourself.

Cheers,

Dave.
-- 
Dave Chinner
david@fromorbit.com

_______________________________________________
xfs mailing list
xfs@oss.sgi.com
http://oss.sgi.com/mailman/listinfo/xfs