Re: [PATCH 14/38] Remove struct mm_struct::exe_file et al

[Andrew Morton <akpm@linux-foundation.org>]

On Sun, 31 May 2009 16:15:50 -0700 (PDT) Linus Torvalds <torvalds@linux-foundation.org> wrote:

> 
> 
> On Sun, 31 May 2009, Andrew Morton wrote:
> > 
> > What I always find a bit weird is that an MM container is used as the
> > central point for a number of sched obects.  But it's logical, given
> > that the never-before-stated definition of a heavyweight process is
> > "thing which share a VM".
> 
> It has nothing to do with "heavy-weight process" or anything else.
> 
> The thing is, from a scheduling standpoint, one of the primary performance 
> concerns in the TLB switch.
> 
> And there's a 1:1 relationship between TLB switch and MM container, modulo 
> the issue of kernel tasks (and those obviously "borrow" approproate MM 
> structs to avoid the switch).

That's all an obscure performance-oriented internal implementation detail.

> So it's not weird at all. It's very direct, and a very straightforward and 
> obvious relationship.

It's arbitrary!  If we were to gain more performance benefit by
aggregating processes under, say, the fs_struct then that's the way the
kernel would have been implemented.