Dear Genode-main readers, I am working on my thesis to implement a real-time capable checkpoint/restore mechanism in Genode/L4-Fiasco.OC on the Chair of Operating Systems, TUM Department of Informatics. A checkpoint-component A has to transparently (more or less) store the internal state of another component B and restore it on another machine also running Genode.
One aspect of the thesis is to store the (virtual) memory pages of B only if they were changed since the last checkpoint (known as "incremental checkpointing"). This means, I have to mark a page if it was used by a write access and unmark it after the checkpoint. This approach is similar to the dirty-bit mechanism in the MMU. By searching the genode-main mailing list I found an idea for emulating the dirty-bit mechanism. In the message [1], the author suggests the use of managed dataspaces and a custom RAM service. The RAM server detaches a dataspace which a client is using, re-attaches and marks the dataspace when the client wants to read it or write to it. Thus, the server of the RAM service notices whenever a client uses a specific dataspace. [1] https://sourceforge.net/p/genode/mailman/message/34787057/ The problem of this approach is the granularity of the dataspaces. I want to be notified when a virtual memory page is changed and store only this page. But using one RM session per 4 KiB dataspace (typical page size) is not efficient, because an RM session uses 64 KiB for itself. * Do I understand this approach correctly? * Is there another way to be notified when a virtual memory page is accessed? * If not, is it possible to extend the core with this mechanism. If yes, which modules are involved? Kind regards Denis ------------------------------------------------------------------------------ Attend Shape: An AT&T Tech Expo July 15-16. Meet us at AT&T Park in San Francisco, CA to explore cutting-edge tech and listen to tech luminaries present their vision of the future. This family event has something for everyone, including kids. Get more information and register today. http://sdm.link/attshape _______________________________________________ genode-main mailing list genode-main@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/genode-main
