Not logged in
Log in now
Create an account
Subscribe to LWN
LWN.net Weekly Edition for May 23, 2013
An "enum" for Python 3
An unexpected perf feature
LWN.net Weekly Edition for May 16, 2013
A look at the PyPy 2.0 release
Memory power management power savings test
Posted Jun 10, 2011 15:05 UTC (Fri) by ccurtis (guest, #49713)
Perhaps I was a bit too terse.
The amount of power actually saved is a bit unclear; estimates seem to run in the range of 5-15% of the total power used by the memory subsystem.
A recent patch set from Ankita Garg does not attempt to solve the whole problem; instead, it creates an initial infrastructure which can be used for future power management decisions.
Before creating this extensive infrastructure, perhaps it would be better to get an idea of what kind of power savings this actually provides. Code would still need to be written to power down the memory bank, and code would also likely need to be written to isolate the excluded RAM from the boot parameter, but this seems like a relatively easy way to answer the question before embarking on the endeavor.
Of course, this may be a done deal and it's just a matter of time before the code gets written, but it would still be interesting to see how much power is actually going to be saved. A patch like this would allow individuals to measure the power savings of their own systems as well, in case they wanted to control the trade of any overhead the new memory management changes might impose.
Posted Jun 10, 2011 16:20 UTC (Fri) by etienne (subscriber, #25256)
Posted Jun 11, 2011 3:19 UTC (Sat) by willy (subscriber, #9762)
As I understand PASR, one would not power down an entire DIMM, but rather sections of each DIMM, thus preserving the performance benefits of interleaving.
Posted Jun 16, 2011 4:54 UTC (Thu) by Ankita (subscriber, #39147)
Copyright © 2013, Eklektix, Inc.
Comments and public postings are copyrighted by their creators.
Linux is a registered trademark of Linus Torvalds