Messages in this thread | | | From | David Mosberger <> | Date | Mon, 5 Aug 2002 22:01:16 -0700 | Subject | RE: large page patch (fwd) (fwd) |
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>>>>> On Mon, 5 Aug 2002 16:30:54 -0700 , "Seth, Rohit" <rohit.seth@intel.com> said:
Rohit> I'm afraid you may be wasting a lot of extra memory by Rohit> replicaitng these PTEs(Take an example of one 4G large TLB Rohit> size entry and assume there are few hunderd processes using Rohit> that same physical page.)
In my opinion, this is perhaps the strongest argument *for* a separate "giant page" syscall interface. It will be very hard (perhaps impossible) to optimize superpages to work efficiently when the ratio of superpage/basepage grows huge (as, by definition, the kernel would manage them as a set of basepages). For example, even if we used a base page-size of 64KB, a 4GB giant page (as supported by Itanium 2) would correspond to 65536 base pages. A superpage of this size would almost certainly still do a lot better than 65536 base pages, but compared to a single giant page, it probably stands no chance performance-wise.
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