Re: [Patch] Cacheline align xlog_t

[Timothy Shimmin <tes@xxxxxxx>]

Andi Kleen wrote:
> On Thu, Apr 03, 2008 at 08:23:47AM +1000, David Chinner wrote:
> > > For the dynamic allocation you would rather need to make sure it
> > > starts at a cache line boundary explicitely because the allocator doesn't
> > > know the alignment of the target type, otherwise your careful
> > > padding might be useless.
> > There isn't one, right?
> You can always align yourself with kmalloc (or any other arbitary 
> size allocator) with the standard technique:
> get L1_CACHE_BYTES-1 or possibly better cache_line_size() - 1 bytes
> more and then align the pointer manually with ALIGN. Only tricky part
> is that you have to undo the alignment before freeing.
Yeah, how do you know how much was offset for the alignment
to go back for the freeing. I guess you could also keep the original pointer
or the offset handy (a pain). Or can the allocator help out?

--Tim