DATE: Thursday , January 17,2002
TIME: Noon - 1 pm
PLACE: Wean Hall 8220

Chris Lumb
Carnegie Mellon University

Freeblock Scheduling Outside of Disk Firmware

This talk will describe the design and implementation of freeblock scheduling outside of disk firmware. Freeblock scheduling is a method for filling rotational latency delays with useful background media transfers without any impact on foreground service times. The freeblock scheduler does this by identifying the rotational latency periods in a foreground request and determining which background media transfers best fit the rotational latency. To do this, the freeblock scheduler must be able to very accurately predict the service time components of any given disk request. Previously this accuracy was not believed possible outside of disk firmware.

We implemented a working external freeblock scheduler as both a user level Linux application and inside the FreeBSD kernel. This implementation has been shown to provide 15% of the full media bandwidth to the background task with almost no impact on the foreground request response times. This results in a 6X increase in disk bandwidth utilization

Chris Lumb is a 4th year Ph.D. student in ECE at Carnegie Mellon University. Chris received his M.S. in 2000 and his B.S. in 1998 from CMU. His current research focuses on storage systems, disk scheduling and new storage interfaces. Chris is a student of Greg Ganger and currently working on Freeblock Disk scheduling. Now in his 8th year at CMU, Chris is looking forward to experiencing what others call 'life outside of CMU'.

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