Re: [PATCH 0/5] make *_gate_vma accept mm_struct instead of task_struct II

Andi Kleen
2011-03-10T17:03:45Z

On Thu, Mar 10, 2011 at 11:54:14AM -0500, Stephen Wilson wrote:
>
> On Thu, Mar 10, 2011 at 08:38:09AM -0800, Andi Kleen wrote:
> > On Thu, Mar 10, 2011 at 08:00:32AM -0800, Andi Kleen wrote:
> > > On Tue, Mar 08, 2011 at 07:31:56PM -0500, Stephen Wilson wrote:
> > > > The only architecture this change impacts in any significant way is x86_64.
> > > > The principle change on that architecture is to mirror TIF_IA32 via
> > > > a new flag in mm_context_t.
> > >
> > > The problem is -- you're adding a likely cache miss on mm_struct for
> > > every 32bit compat syscall now, even if they don't need mm_struct
> > > currently (and a lot of them do not) Unless there's a very good
> > > justification to make up for this performance issue elsewhere
> > > (including numbers) this seems like a bad idea.
> >
> > Hmm I see you're only setting it on exec time actually on rereading
> > the patches. I thought you were changing TS_COMPAT which is in
> > the syscall path.
> >
> > Never mind. I have no problems with doing such a change on exec
> > time.
>
> OK. Great! Does this mean I have your ACK'ed by or reviewed by?

I didn't read it all, but the first two patches looked ok.

-Andi