On Wed, 11 Sep 2013, Eric Sandeen wrote:

quoted

The reason why I'm pushing here is that mbcache shouldn't be showing
up in the profiles at all if there is no external xattr block.  And so
if newer versions of SELinux (like Adnreas, I've been burned by
SELinux too many times in the past, so I don't use SELinux on any of
my systems) is somehow causing mbcache to get triggered, we should
figure this out and understand what's really going on.

selinux, from an fs allocation behavior perspective, is simply setxattr.

what you are missing is that Ted is saying that unless you are using xattrs, the 
mbcache should not show up at all.

The fact that you are using SElinux, and SELinux sets the xattrs is what makes 
this show up on your system, but other people who don't use SELinux (and so 
don't have any xattrs set) don't see the same bottleneck.

David Lang