, January 17,2002
Noon - 1 pm
Wean Hall 8220
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
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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