On 09/26/2013 06:44 AM, Arjan van de Ven wrote: > On 9/25/2013 4:47 PM, Andi Kleen wrote: >>> Also, the changelogs don't appear to discuss one obvious downside: the >>> latency incurred in bringing a bank out of one of the low-power states >>> and back into full operation. Please do discuss and quantify that to >>> the best of your knowledge. >> >> On Sandy Bridge the memry wakeup overhead is really small. It's on by >> default >> in most setups today. > > yet grouping is often defeated (in current systems) due to hw level > interleaving ;-( > sometimes that's a bios setting though. > True, and I plan to tweak those hardware settings in the prototype powerpc platform and evaluate the power vs performance trade-offs of various interleaving schemes in conjunction with this patchset. > in internal experimental bioses we've been able to observe a "swing" of > a few watts > (not with these patches but with some other tricks)... Great! So, would you have the opportunity to try out this patchset as well on those systems that you have? I can modify the patchset to take memory region info from whatever source you want me to take it from and then we'll have realistic power-savings numbers to evaluate this patchset and its benefits on Intel/x86 platforms. > I'm curious to see how these patches do for Srivatsa > As I mentioned in my other mail, I don't yet have a setup for doing actual power-measurements. Hence, so far I was focussing on the algorithmic aspects of the patchset and was trying to get an excellent consolidation ratio, without hurting performance too much. Going forward, I'll work on getting the power-measurements as well on the powerpc platform that I have. Regards, Srivatsa S. Bhat -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>