[ltt-dev] Porting "jump labels" to userspace

Mathieu Desnoyers mathieu.desnoyers at efficios.com
Wed Feb 16 15:39:53 EST 2011

* David Daney (ddaney at caviumnetworks.com) wrote:
> On 02/16/2011 12:04 PM, Roland McGrath wrote:
>> IMHO there is not really so much to the in-kernel implementation that it's
>> worth attempting to reuse the code in userland.  Pretty much all the work
>> is in the details of the implementation that would naturally differ a lot
>> in a different context.  If you understand the mechanism and the machine
>> details, then implementing it well for a userland context is not a big deal
>> and is cleaner to do from scratch than shoe-horning kernel-centric code
>> into a wildly different context.
> Good point.
> Certainly the details of maintaining instruction cache coherency may be  
> different in userspace.

Indeed, the arch-specific parts will need some extra care (which might, in the
worse case scenario, require to suspend a whole process during the update), but
the generic code in jump_label.c and jump_label.h could certainly be reused.



> David Daney

Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.

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