kvm_read() vs ioctl performance

Julian Elischer julian at elischer.org
Fri Mar 21 11:42:30 PDT 2008

Barney Cordoba wrote:
> I have an app which reads stats from the kernel
> periodically, and there can be a lot of iterations,
> sometimes 20,000 or more. I'm thinking of converting
> from an ioctl method to kvm_read(). KVM is certainly
> simpler, but its not clear what overhead is involved,
> since kvm_read() likely has to call the kernel also.
> Does anyone have a handle on the difference in
> overhead, assuming that the ioctl call is to a module
> which does nothing more than copy the data and return?

tried a shared memory page?

> Thanks,
> barney
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