Messages in this thread | | | Date | Thu, 6 Feb 2014 06:42:09 +0100 | From | Ingo Molnar <> | Subject | Re: [RFC] de-asmify the x86-64 system call slowpath |
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:
> [...] > > No, I was thinking "try to optimistically map 8 adjacent aligned > pages at a time" - that would be the same cacheline in the page > tables, so it would be fairly cheap if we couple it with a > gang-lookup of the pages in the page cache (or, for anonymous pages, > by just optimistically trying to do an order-3 page allocation, and > if that works, just map the 32kB allocation you got as eight > individual pages). > > I know it's been discussed at some point, and I even have a dim > memory of having seen some really ugly patches.
I have a dim memory of having written such group-prefaulting patches myself a decade ago or so - IIRC the main problem was that at that time we never found a common load where it really mattered, and it was easy to spend more time doing all this extra work and not see the prefaulted pages used.
But the cost/benefit balance has indeed changed so IMO it's worth a try.
Thanks,
Ingo
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