On Mon, Apr 25, 2016 at 11:04:38AM -0700, Vikas Shivappa wrote:
> >This is a 'creative' solution; why don't you do the normal thing, which
> >is:
> >
> >start:
> > prev_count = read_hw_counter();
> >
> >read:
> > do {
> > prev = prev_count;
> > cur_val = read_hw_counter();
> > delta = cur_val - prev;
> > } while (local_cmpxchg(&prev_count, prev, cur_val) != prev);
> > count += delta;
>
>
> I may need to update the comment.
>
> rc_count stores the total bytes for RMIDs that were used for this event
> except for the count of current RMID.
Yeah, I got that, eventually.
> Say an event used RMID(1) .. RMID(k) from init to read and it had RMID(k)
> when read was called, the rc_count stores the values read from RMID1 ..
> RMID(k-1).
>
> For MBM the patch is trying to do:
> count
> = total_bytes of RMID(1) + ... +total_bytes of RMID(k-1) + total_bytes of
> RMID(k))
> = rc_count + total_bytes of RMID(k).
How is the regular counting scheme as outlined above not dealing with
this properly?
