Re: [PATCH] allocation looping + kswapd CPU cycles

[Marcelo Tosatti]

On Wed, 9 May 2001, Mark Hemment wrote:

> 
> On Tue, 8 May 2001, David S. Miller wrote: 
> > Actually, the change was made because it is illogical to try only
> > once on multi-order pages.  Especially because we depend upon order
> > 1 pages so much (every task struct allocated).  We depend upon them
> > even more so on sparc64 (certain kinds of page tables need to be
> > allocated as 1 order pages).
> > 
> > The old code failed _far_ too easily, it was unacceptable.
> > 
> > Why put some strange limit in there?  Whatever number you pick
> > is arbitrary, and I can probably piece together an allocation
> > state where the choosen limit is too small.
> 
>   Agreed, but some allocations of non-zero orders can fall back to other
> schemes (such as an emergency buffer, or using vmalloc for a temp
> buffer) and don't want to be trapped in __alloc_pages() for too long.
> 
>   Could introduce another allocation flag (__GFP_FAIL?) which is or'ed
> with a __GFP_WAIT to limit the looping?

__GFP_FAIL is in the -ac tree already and it is being used by the bounce
buffer allocation code.