Messages in this thread | | | Date | Tue, 24 Oct 2023 12:14:25 -0700 | From | "H. Peter Anvin" <> | Subject | RE: [PATCH v2 1/6] x86/bugs: Add asm helpers for executing VERW |
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On October 24, 2023 11:49:07 AM PDT, "Luck, Tony" <tony.luck@intel.com> wrote: >> the only overhead to modules other than load time (including the runtime linking) is that modules can't realistically be mapped using large page entries. > >If there were some significant win for using large pages, couldn't the >kernel pre-allocate some 2MB pages in the [-2GiB,0) range? Boot parameter >for how many (perhaps two for separate code/data pages). First few loaded >modules get to use that space until it is all gone. > >It would all be quite messy if those modules were later unloaded/reloaded >... so there would have to be some compelling benchmarks to justify >the complexity. > >That's probably why Peter said "can't realistically". > >-Tony >
Sure it could, but it would mean the kernel is sitting on an average of 6 MB of unusable memory. It would also mean that unloaded modules would create holes in that memory which would have to be managed.
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