Re: [patch 1/3] slob: rework freelist handling

Christoph Lameter
2007-05-24T04:23:22Z

On Thu, 24 May 2007, Nick Piggin wrote:

> > It would also work fine with SLUB? Its about 12k code + data on
> > x86_64. I doubt that this would be too much of an issue.
>
> Well as I said, I am not the one to ask about whether SLUB could replace
> SLOB or not. All else being equal, of course it is a good idea.
>
> But what I think is clear is that SLOB simply uses memory more
> efficiently than SLUB (in my test, anyway). I don't know how this can
> still be in dispute?

You have shown that SLUB used more memory than SLOB after bootup on PPC64.
But why is still an open question.

It could be the way that SLOB can exploit the page for multiple object
sizes which creates the advantage. If that is the case then we can do
nothing with SLUB.

But there could still be excessive memory allocs with SLUB that we are not
aware of at this point. For example if the page size > 4k then SLUB will
use higher order allocs by default which will increase wastage.