Messages in this thread | | | Date | Tue, 3 Apr 2007 19:35:05 +0200 | From | Andi Kleen <> | Subject | Re: getting processor numbers |
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On Tue, Apr 03, 2007 at 10:30:47AM -0700, Ulrich Drepper wrote: > Andi Kleen wrote: > > Topology is dependent on the number of CPUs. > > Not all of it.
What is not?
> We might add very limited caching (for a few > seconds) but that's as much as we can go.
Hmm, e.g. in OpenMP you would have another thread that just reads /proc/cpuinfo in a loop and starts new threads on new CPUs?
That sounds ...... "expensive"
The other use case in glibc I know of is the Opteron optimized memcpy which can use different functions depending on the number of cores. But having a separate thread regularly rereading cpuinfo for memcpy also sounds quite crazy.
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