Messages in this thread | | | Date | Sun, 16 Apr 2006 16:35:09 +1000 | From | Paul Mackerras <> | Subject | Re: [PATCH 00/05] robust per_cpu allocation for modules |
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Steven Rostedt writes:
> The data in .data.percpu_offset holds is referenced by the per_cpu > variable name which points to the __per_cpu_offset array. For modules, > it will point to the per_cpu_offset array of the module. > > Example: > > DEFINE_PER_CPU(int, myint); > > would now create a variable called per_cpu_offset__myint in > the .data.percpu_offset section. This variable will point to the (if > defined in the kernel) __per_cpu_offset[] array. If this was a module > variable, it would point to the module per_cpu_offset[] array which is > created when the modules is loaded.
This sounds like you have an extra memory reference each time a per-cpu variable is accessed. Have you tried to measure the performance impact of that? If so, how much performance does it lose?
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