Re: slab: introduce the flag SLAB_MINIMIZE_WASTE

[Christopher Lameter]

On Tue, 17 Apr 2018, Mikulas Patocka wrote:

> > > The slub subsystem does actual fallback to low-order when the allocation
> > > fails (it allows different order for each slab in the same cache), but
> > > slab doesn't fallback and you get NULL if higher-order allocation fails.
> > > So, SLAB_MINIMIZE_WASTE is needed for slab because it will just randomly
> > > fail with higher order.
> >
> > Fix Slab instead of adding a flag that is only useful for one allocator?
>
> Slab assumes that all slabs have the same order, so it's not so easy to
> fix it.

Well since SLAB uses compound pages one could easily determine the order
of the page and thus also support multiple page orders there.