On Thu, 2006-11-30 at 11:33 -0800, Christoph Lameter wrote:

On Thu, 30 Nov 2006, Peter Zijlstra wrote:

quoted

No, the forced allocation is to test the allocation hardness at that
point in time. I could not think of another way to test that than to
actually to an allocation.

Typically we do this by checking the number of free pages in a zone 
compared to the high low limits. See mmzone.h.

This doesn't work under high load because of direct reclaim. And if I go
run direct reclaim to test if I can raise the free pages level to an
acceptable level for the given gfp flags, I might as well do the whole
allocation.