Messages in this thread |  | | Date | Sat, 28 Jun 2003 17:34:05 -0700 | From | "Martin J. Bligh" <> | Subject | Re: 2.5.73-mm2 |
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--Christoph Hellwig <hch@infradead.org> wrote (on Saturday, June 28, 2003 17:08:37 +0100):
> On Sat, Jun 28, 2003 at 08:54:36AM -0700, William Lee Irwin III wrote: >> +config HIGHPMD >> + bool "Allocate 2nd-level pagetables from highmem" >> + depends on HIGHMEM64G >> + help >> + The VM uses one pmd entry for each pagetable page of physical >> + memory allocated. For systems with extreme amounts of highmem, >> + this cannot be tolerated. Setting this option will put >> + userspace 2nd-level pagetables in highmem. > > Does this make sense for !HIGHPTE? In fact does it make sense to > carry along HIGHPTE as an option still? ..
Last time I measured it, it had about a 10% overhead in kernel time. Seems like a good thing to keep as an option to me. Bill said he had some other code to alleviate the overhead, but I don't think it's merged ... I'd rather see UKVA (permanently map the pagetables on a per-process basis) merged before it becomes "not an option" - that gets rid of all the kmapping.
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