Re: [PATCH 04/10] mm: slub: add knowledge of reserve pages

Christoph Lameter
2007-08-08T17:57:27Z

On Wed, 8 Aug 2007, Andrew Morton wrote:

> 3. Perform page reclaim from hard IRQ context. Pretty simple to
> implement, most of the work would be needed in the rmap code. It might be
> better to make it opt-in via a new __GFP_flag.

In a hardirq context one is bound to a processor and through the slab
allocator to a slab from which one allocates objects. The slab is per cpu
and so the slab is reserved for the current context. Nothing can take
objects away from it. The modifications here would not be needed for that
context.

I think in general irq context reclaim is doable. Cannot see obvious
issues on a first superficial pass through rmap.c. The irq holdoff would
be pretty long though which may make it unacceptable.