Re: Porting "jump labels" to userspace

From: Mathieu Desnoyers
Date: Wed Feb 16 2011 - 15:40:01 EST


* David Daney (ddaney@xxxxxxxxxxxxxxxxxx) 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.

Thanks,

Mathieu

>
> David Daney

--
Mathieu Desnoyers
Operating System Efficiency R&D Consultant
EfficiOS Inc.
http://www.efficios.com
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