Re: [patch] swap-speedup-2.4.3-B3

[Linus Torvalds <torvalds@transmeta.com>]

On Tue, 24 Apr 2001, Ingo Molnar wrote:
> 
> the latest swap-speedup patch can be found at:

Please don't add more of those horrible "wait" arguments.

Make two different versions of a function instead. It's going to clean up
and simplify the code, and there really isn't any reason to do what you're
doing.

You should split up the logic differently: if you want to wait for the
page, then DO so:

	page = lookup_swap_cache(..);
	if (page) {
		wait_for_swap_cache:valid(page);
		.. use page ..
	}

Note how much more readable and UNDERSTANDABLE the above is, compared to

	page = lookup_swap_cache(..., 1);
	if (page) {
		...

and note also how splitting up the waiting will

 - simplify the swap cache lookup function, making it faster for people
   who do _NOT_ want to wait.

 - make it easier to statically check the correctness of programs by just
   eye-balling them ("Hey, he's calling 'wait' with the spinlock held").

 - more easily moving the wait around, allowing for more concurrency.

Basically, I don't want to mix synchronous and asynchronous
interfaces. Everything should be asynchronous by default, and waiting
should be explicit.

		Linus

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