On 10/11/2011 11:12 AM, Alan Cox wrote:
On 10/10/2011 16:28, Wojciech Puchar wrote:
is it possible to force VM subsystem to operate on superpages when
possible - i mean swapping in 2MB chunks?
Currently, no. For some applications, like the Sun/Oracle JVM, that
have code to explicitly manage large pages, there could be some
benefit in the form of reduced overhead. So, it's on my "to do" list,
but no where near the top of that list.
Alan
Am I correct in remembering that super-pages have to be aligned on the
super-page boundary and be contiguous?
If so, in the mmap(), he may want to include the 'MAP_FIXED' flag with
an address that is on a super-page boundary. Right now, the
"VMFS_ALIGNED_SPACE" that does the VA super-page alignment is only used
for device pagers.
Similarly, if the allocated physical pages for the object are not
contiguous, then MAP_PREFAULT_READ will not result in a super-page
promotion.
--Mark Tinguely
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