Messages in this thread | | | Date | Wed, 25 Jul 2007 17:25:12 +1000 | From | Nick Piggin <> | Subject | Re: -mm merge plans for 2.6.23 |
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david@lang.hm wrote: > On Wed, 25 Jul 2007, Nick Piggin wrote:
>> And constructed test cases of course are useful as well, I didn't say >> they weren't. I don't know what you mean by "acceptable", but you should >> read my last paragraph again. > > > this problem has been around for many years, with many different people > working on solutions. it's hardly a case of getting a proposal and > trying to get it in without anyone looking at other options.
What is "this problem"? People have an updatedb problem that is solved by swap prefetching which I want to fix in a different way.
There would be a different problem of "run something that uses heaps of memory and swap everything else out, then quit it, wait for a while, and swap prefetching helps". OK, definitely swap prefetching would help there. How much? I don't know. I'd be slightly surprised if it was like an order of magnitude, because not only swap but everything else has been thrown out too.
> it seems that there are some people (not nessasarily including you) who > will oppose this feature until a test is created that shows that it's > better. the question is what sort of test will be accepted as valid? I'm > not useing this patch, but it sounds as if the people who are useing it > are interested in doing whatever testing is required, but so far the > situation seems to be a series of "here's a test", "that test isn't > valid, try again" loops. which don't seem to be doing anyone any good
And yet despite my repeated pleas, none of those people has yet spent a bit of time with me to help analyse what is happening.
> and are frustrating lots of people, so like several people over the last > few days O'm asking the question, "what sort of test would be acceptable > as proof that this patch does some good?"
I don't think any further proof is needed that the patch does "some" good. Rig up a test case and you could see some seconds shaved off it. Maybe you want to know "how to get this patch merged"? And I don't know that one. I do know that it is fuzzy, and probably doesn't include demanding things of Andrew or Linus.
BTW. If you find out the answer to that one, let me know because I have this lockless pagecache patch that has also been around for years, is also just a few hundred lines in the VM, and does do some good too. I'm sure the buffered AIO people and many others would also like to know.
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