Messages in this thread | | | Date | Sun, 27 Feb 2011 12:53:50 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH 2/2] x86,mm,64bit: Round up memory boundary for init_memory_mapping_high() |
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* Tejun Heo <tj@kernel.org> wrote:
> > will have problem with cross node conf. like 0-4g, 8-12g on node0, 4g-8g, > > 12g-16g on node1. > > And how common are they? This whole cruft is basically meaningless if 1GiB > mapping is supported, IOW, basically on all AMD 64s and all post-nehalem intels. > Why not just cite the limitation in the comment and stick to something simple?
Such complexity should be justified via very careful "perf stat --repeat" measurements.
I.e. showing 'before patch' and 'after patch' instruction, TLB miss and cycle counts, showing that a positive effect that goes beyond the noise of the measurement exists.
1GB mappings should be assumed as the common case - anything else probably does not matter from a future performance/scalability POV. For vmalloc() it might make sense - but even for those precise measurements should be done about the positive effect.
Thanks,
Ingo
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