On Tue, Aug 28, 2007 at 01:19:42PM +0200, Jean Delvare wrote: > Hi Darrick, hi Henrique, > > Good thing that manufacturers start including wattmeters in their > hardware. Hopefully this will help users better control their power > consumption in the long run. Yes, we're working on that too. :) > > What unit should we use? Watts are way, way too big as there is no > > floating/fixed point in sysfs. 10^-6 W is probably what is called for, > > since we already need 10^-3 V and 10^-3 A. Small portable devices can > > easily draw less than 10^-3 W nowadays. > > Good point. The driver currently exports non-integer values, which is > not acceptable, so indeed it needs to be changed. We want at least a I had a feeling you might say that. :) I'll post a follow-up patch that presents the power meters in mW instead of W. > resolution of 10^-3 W. Not sure about 10^-6 W. I am surprised that > portable devices can really draw less than 1 mW, and be it the case, I Are there meters that can measure that small a quantity of power? If so, then I'll vote for uW; otherwise, mW is fine enough for me. > doubt that manufacturers will embed a wattmetter: it would probably > draw more current than the rest of the device ;) so it may not be > relevant for our decision. > > So I think I'd go with 10^-3 W, but I welcome diverging opinions. Out > of curiosity, what is the physical resolution of IBM's device? I don't know for sure, but my observation is that they're no more accurate than a Watt. Some of those meters appear to be averages, which would explain why they occasionally have deciWatt components. > I see that the driver relies on IPMI. Can't it be merged with the > out-of-tree impisensors driver then? This would give that driver some > momentum so that it can finally be merged, and I would like to avoid > having two drivers if one is enough. Note though that I don't know > anything about IPMI so I might as well be totally wrong ;) The IBM PEx meters are accessible via custom IPMI commands, not the standard IPMI sensor interface. I considered modifying the ipmisensors driver, but reached the opinion that it would clutter that driver unnecessarily, particularly since there are a lot of systems with IPMI BMCs, but most of them will not have this interface. That said, what is standing in the way of ipmisensors being merged? I think I can shake out some free time to apply TLC. --D -------------- next part -------------- A non-text attachment was scrubbed... Name: not available Type: application/pgp-signature Size: 189 bytes Desc: Digital signature Url : http://lists.lm-sensors.org/pipermail/lm-sensors/attachments/20070828/b020f4c6/attachment.bin
