Re: how not to write a search algorithm

[William Lee Irwin III <wli@holomorphy.com>]

On Sun, Aug 04, 2002 at 03:43:56PM -0700, Andrew Morton wrote:
> Getting the kernel back to the level of performance and stability
> which it had before the rmap patch has to be the first step.
> 1) 50% increase in system load on fork/exec/exit workloads
> 2) Will oops on pte_chain oom
> 3) pte_highmem is bust
> 4) tripled ZONE_NORMAL consumption
> 5) pte chains go wrong with ntpd
> The first three or four here are fatal to the retention of the
> reverse map, IMO.  Futzing around fixing them is taking time
> and is holding up other work.
> I may have a handle on 1).  Still working it.

(2) only needs the reservation bits from the preceding post if it's
	just dealing with kmem_cache_alloc() returning NULL.
(3) I ground out the half-assed quick & dirty "fish the pfn out of the
	kmap pte" a.k.a. virt_to_fix() and use physaddrs in pte_chains
	thingie and handed it off to others to debug/clean up/push.
(4) is part of the known tradeoff AFAIK, but phillips may have something
	taking it down to only double or so

Cheers,
Bill
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