Re: [PATCH 8/9] mm: implement split page table lock for PMD level

[Peter Zijlstra]

On Fri, Sep 13, 2013 at 05:25:13PM +0300, Kirill A. Shutemov wrote:
> Peter Zijlstra wrote:
> > On Fri, Sep 13, 2013 at 04:06:15PM +0300, Kirill A. Shutemov wrote:
> > > The basic idea is the same as with PTE level: the lock is embedded into
> > > struct page of table's page.
> > > 
> > > Split pmd page table lock only makes sense on big machines.
> > > Let's say >= 32 CPUs for now.
> > 
> > Why is this? Couldn't I generate the same amount of contention on PMD
> > level as I can on PTE level in the THP case?
> 
> Hm. You are right. You just need more memory for that.
> Do you want it to be "4" too?

Well, I would drop your patch-1 and use the same config var.
--
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/