Re: [patch 3/6] mm: speculative get page

[Christoph Lameter <clameter@sgi.com>]

On Tue, 13 Nov 2007, Nick Piggin wrote:

> > Good idea. That avoids another page bit.
> 
> Yeah, it's Hugh's good idea. It avoids smp_rmb() in the find_get_page
> path as well, which will be helpful at least for things like powerpc
> and ia64, if not x86. At one single atomic operation to lookup and take
> a reference on a pagecache page, I think it is approaching the fastest
> possible implementation ;)

Well I hope all locations that do get_page_unless_zero are aware that a 
failure does not mean that the page is being freed.

> > Looks okay but I think you could remove the earlier performance check. We 
> > already modified the page struct by obtaining the page lock so we hold it 
> > exclusively. And the failure rate here is typicalyvery low.
> 
> It's up to you. Honestly, I don't have good test facilities for page
> migration. If it's all the same to you, do you mind if we leave it like
> this, and then you can change it in future?

Ok. Lee will likely get to that ;-).

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>