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Re: [PATCH] memset.S and PowerPC
> From: Andreas Jaeger <aj@suse.de>
> Date: Tue, 18 Jun 2002 18:03:15 +0200
> "Steve Munroe" <sjmunroe@us.ibm.com> writes:
>
> > Andreas Jaeger writes:
> >>> Do you really want a nop here?
> >
> > I am not sure but the base code is full of comments like:
> >
> > /* 40th instruction from .align */
> >
> > Which implies that the alignment of code (within the i-cache) was
> > important. While this is likely only an important issue for early (601,
> > 603, ...) PowerPC processors, I wanted to avoid messing with the implied
> > magic. This is not an important issue for the 64-bit PowerPC
>
> In that case just add this as a comment along the nop (if that's the
> final solution)
Actually, even the nop will slightly affect the schedule. The
code is hand-scheduled for the 601. I think a nop will have the least
impact. You'd want to add a comment saying why it is there.
> > implementations which I am most familiar. Perhaps Geoff remembers the
> > background on this? Does this still matter for the current inventory of
> > Linux/PowerPC systems in use today?
> >
> >>> Can you send a clean, working patch, please?
> >
> > I can, but do you want this patch or the more comprehensive solution that
> > deals with dcbz for different cache-line sizes?
>
> Geoff or Ulrich have the final ok here. My personal opionion would be
> the "more comprehensive" solution. Geoff, what do you think?
If I have a choice, I'd really like the more comprehensive solution!
--
- Geoffrey Keating <geoffk@geoffk.org> <geoffk@redhat.com>