Re: [RFC PATCH] greatly reduce SLOB external fragmentation

malc
2008-07-31T17:55:21Z

Linus Torvalds <torvalds@linux-foundation.org> writes:

> On Thu, 31 Jul 2008, Pekka Enberg wrote:
>>
>> Oh, I didn't suggest this for merging. Just thought you'd be
>> interested to know that best-fit doesn't really do that much better
>> than what we have in the tree now. (Well, I was kinda hoping you'd
>> tell me why my implementation is wrong and you were right all along.)
>
> Heh. Most allocators tend to work pretty well under normal load, and the
> real fragmentation problems all tend to happen under special patterns. The
> one in glibc, for example, sucks donkey dick when using threading, but is
> apparently ok otherwise.
>
> I wouldn't actually expect most "normal" kernel use to show any really bad
> patterns on any normal loads. Google for
>
> worst-case first-fit fragmentation
>
> (or 'next-fit' for that matter) to see some stuff. Of course, it is scary
> only if you can trigger it in practice (perhaps with certains games on
> packet size, or creating/removing files with pathname size patterns ec).
>
> [ Of course, google probably mostly returns hits from all those ACM
> portals etc. I wonder why google does that - they're almost totally
> useless search results. Sad. If somebody knows how to turn those ACM
> pay-portals off in google, pls let me know ]
>
> Linus

blahblah -site:portal.acm.org ?

--
mailto:av1474@comtv.ru