Messages in this thread | | | Date | Wed, 31 Aug 2005 08:39:13 -0700 | From | "Martin J. Bligh" <> | Subject | Re: [PATCH 1/1] Implement shared page tables |
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>> They're incompatible, but you could be left to choose one or the other >> via config option. > > Wouldn't need config option: there's /proc/sys/kernel/randomize_va_space > for the whole running system, compatibility check on the ELFs run, and > the infinite stack rlimit: enough ways to suppress randomization if it > doesn't suit you.
Even better - much easier to deal with distro stuff if we can do it at runtime.
>> 3% on "a certain industry-standard database benchmark" (cough) is huge, >> and we expect the benefit for PPC64 will be larger as we can share the >> underlying hardware PTEs without TLB flushing as well. > > Okay - and you're implying that 3% comes from _using_ the shared page > tables, rather than from avoiding the fork/exit overhead of setting > them up and tearing them down. And it can't use huge TLB pages > because... fragmentation?
Yes - as I understand it, that was a straight measurement with/without the patch, and the shmem segment was already using hugetlb (in both cases). Yes, I find that a bit odd as to why as well - they are still trying to get some detailed profiling to explain.
M.
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