Re: [PATCH][RFC] 4K stacks default, not a debug thing any more...?

From: Rene Herman
Date: Wed Jul 18 2007 - 13:34:15 EST


On 07/18/2007 07:19 PM, Phillip Susi wrote:

Why do the two pages have to be physically contiguous? The stack just needs to be two contiguous pages in virtual memory, but they can map to any two pages anywhere in physical memory.

As far as I'm aware that's just a consequence of the way linux does memory management. If we ignore highmem, virtual memory is simply +/- PAGE_OFFSET away from physical so allocating virtually contiguous pages that are _not_ physically contiguous requires mapping them somewhere (the vmalloc area) which is limited. Given that large number of threads _are_ the problem you wouldn't solve things -- you'd again be out of space, although now for a different reason.

Rene.
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