svn commit: r242402 - in head/sys: kern vm

[Jim Harris]

On Wed, Oct 31, 2012 at 3:55 PM, Attilio Rao <attilio at freebsd.org> wrote:

> On Wed, Oct 31, 2012 at 8:31 PM, Andre Oppermann <andre at freebsd.org>
> wrote:
> > You can define CACHE_LINE_SIZE to 0 on those platforms.
> > Or to make it even more granular there could be a CACHE_LINE_SIZE_LOCKS
> > that is used for lock padding.
>
> I think that this is a bright idea, albeit under the condition that
> just like CACHE_LINE_SIZE it won't change during STABLE branches
> timeframe and that it must not be dependent by SMP option.
>
> What do you think about this patch?:
> http://www.freebsd.org/~attilio/cache_line_size_locks.patch
>

Should CACHE_LINE_SIZE_LOCKS still be defined as CACHE_LINE_SIZE on arm,
mips, etc. if SMP is enabled?  This would ensure the padding that used to
be there in vpglock doesn't go away.

I'm also wondering if this should be named something different, perhaps
LOCK_ALIGNMENT.

-Jim