Re: [patch 02/23] SLUB: Rename NUMA defrag_ratio to remote_node_defrag_ratio

Matt Mackall
2007-11-08T19:48:03Z

On Thu, Nov 08, 2007 at 11:16:33AM -0800, Christoph Lameter wrote:
> On Thu, 8 Nov 2007, Matt Mackall wrote:
>
> > > I cannot figure out what the number of cycles currently showing on the TSC
> > > have to do with a ratio :(. I could semi-understand if we were counting up
> > > how many cycles were being spent trying to pack objects but that does not
> > > appear to be the case. The comment didn't help a whole lot either. It felt
> > > like a cost for packing, not a ratio
> >
> > It's just a random number generator. And a bad one: lots of arches
> > return 0. And I believe at least one of them has some NUMA support.
>
> Do we have a better one? Something with minimal processing overhead? I'd
> be glad to switch it.

Not really. drivers/char/random.c does:

__get_cpu_var(trickle_count)++ & 0xfff

for a similar purpose.

--
Mathematics is the supreme nostalgia of our time.