Re: [BUG] long freezes on thinkpad t60

[Ingo Molnar]

* Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> wrote:

> On Thu, 21 Jun 2007, Ingo Molnar wrote:
> > 
> > I can understand why no data is saved by this change: gcc is 
> > aligning the next field to a natural boundary anyway and we dont 
> > really have arrays of spinlocks (fortunately).
> 
> Actually, some data structures could well shrink.
> 
> Look at "struct task_struct", for example. Right now it has two 
> spinlocks right next to each other (alloc_lock and pi_lock).

yeah. We've got init_task's task-struct embedded in the vmlinux, but 
it's aligned to 32 bytes, which probably hides this effect. We'd only 
see it if the size change just happened to bring a key data structure 
(which is also embedded in the vmlinux) just below a modulo 32 bytes 
boundary. The chance for that is around 6:32 per 'merge' event. That 
means that there cannot be all that many such cases ;-)

anyway, the shorter init sequence is worth it already.

	Ingo
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/