Re: [PATCH] 2.2.17pre7 VM enhancement Re: I/O performance on 2.4.0-test2

[Andrea Arcangeli <andrea@suse.de>]

On Tue, 11 Jul 2000, Rik van Riel wrote:

>On Tue, 11 Jul 2000, Andrea Arcangeli wrote:
>> On Tue, 11 Jul 2000, Rik van Riel wrote:
>> 
>> >No. You just wrote down the strongest argument in favour of one
>> >unified queue for all types of memory usage.
>> 
>> Do that and download an dozen of iso image with gigabit ethernet
>> in background.
>
>You need to forget about LRU for a moment. The fact that
>LRU is fundamentally broken doesn't mean that it has
>anything whatsoever to do with whether we age all pages
>fairly or whether we prefer some pages over other pages.
>
>If LRU is broken we need to fix that, a workaround like
>your proposal doesn't fix anything in this case.

So tell me how with your design can I avoid the kernel to unmap anything
while running:

	cp /dev/zero .

forever.

Whatever aging algorithm you use if you wait enough time the mapped pages
will be thrown away eventually.

If the above `cp` is able to throw away _everything_ eventually, that will
be a major problem IMHO and I don't agree in using a long-term-design that
can't avoid that so common problem.

Andrea

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