Nick Piggin [off-list ref] wrote:

Andrew Morton wrote:

quoted

Nick Piggin [off-list ref] wrote:

quoted

Previously the ->protection[] logic was broken. It was difficult to follow
and basically didn't use the asynch reclaim watermarks properly.

eh?

Broken how?

min = (1<<order) + z->protection[alloc_type];

This value is used both as the condition for waking kswapd, and
whether or not to enter synch reclaim.

What should happen is kswapd gets woken at pages_low, and synch
reclaim is started at pages_min.

Are you aware of this:

void wakeup_kswapd(struct zone *zone)
{
	if (zone->free_pages > zone->pages_low)
		return;

?

pages_low + protection and pages_min + protection, etc.

Nick, sorry, but I shouldn't have to expend these many braincells
decrypting your work.  Please: much better explanations, more testing
results.  This stuff is fiddly, sensitive and has a habit of blowing up in
our faces weeks later.  We need to be cautious.  The barriers are higher
nowadays.

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