Messages in this thread | | | From | Yuhong Bao <> | Subject | RE: Ubuntu 32-bit, 32-bit PAE, 64-bit Kernel Benchmarks | Date | Sun, 28 Feb 2010 17:31:39 -0800 |
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>> Given that Linus was once talking about the performance penalties of PAE and HIGHMEM64G, perhaps you'd find these benchmarks done by Phoronix of interest: >> http://www.phoronix.com/scan.php?page=article&item=ubuntu_32_pae >> > > The big difference isn't between HIGHMEM4G (no PAE) and HIGHMEM64G > (PAE), it's between HIGHMEM and !HIGHMEM. That cutoff is ~892 MB for a > stock 32-bit kernel. BTW, Linus posted this about HIGHMEM and PAE: http://www.realworldtech.com/forums/index.cfm?action=detail&id=78966&threadid=78766&roomid=2 A few corrections though. HIMEM.SYS was never about memory windowing, EMS was. The way the 286 could access 16MB of memory was plain old segmentation, just in a different way than EMS did. And the main issue with PAE in Windows was driver issues, I think, which is why when they enabled PAE to get the NX bit, they limited physical address space to 32-bit on client versions of Windows.
Yuhong Bao
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