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NetBSD-SoC: A Framework For Enforcing QoS Inside the NetBSD UVM

For latest updates, please visit: http://crewman.uta.edu/~skundu/gsoc_2007.html

What is it?

For delay sensitive systems such as streaming multimedia servers and back-end database systems, servicing the reader processes in a timely fashion is more important than the servicing the writers. This is because applications are blocked from processing unless the data is made available to them by the underlying operating system (OS). Thus, readers need to be serviced instaneously while it does no harm for the writers to wait for a certain amount of time.

However, in commodity a OS such as NetBSD, there occurs no way of enforcing such process prioritization. While it is possible to prioritize the read requests at the IO scheduler level, such approaches are of little or no relevance if the virtual memory (VM) is unable to allocate free pages for the data to be read in.

In this project, we aim to prioritize the readers over the writers so that the transcations-per-second (TPS) of latency senisitve processes can be improved when the system is either experiencing lots of page requests and/or flurry of write activities.  We are currently aiming for two modular approaches: (i) Change the manner in which the pagedaemon removes pages, and (ii) provide feedback about the performance of the I/O queues to the UVM.


!!! Work in Progress !!!


Mandatory (must-have) components:

Optional (would-be-nice) components:


This section will be updated during the first week of July.

Technical Details

This section will be updated during the first week of July.
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Sumantra R. Kundu <sumantra@gmail.com>
$Id: index.html,v 1.3 2007/06/15 03:59:39 sumantra_kundu Exp $