Comments on: Flash drives not worth the candle in notebooks

By: John Bäckstrand

John Bäckstrand — Wed, 05 Dec 2007 22:04:31 +0000

Well, TCP/IP is not light-weight, but that doesnt mean it will use “power” (ie. CPU) unless doing some real heavy lifting? Were you benchmarking the network when the wifi was activated or?

By: Robin Harris

Robin Harris — Tue, 20 Nov 2007 05:47:31 +0000

David, I’ve looked for the presentations you refer to. Send me the links!

Fazal, I didn’t check to see if the gigE was enabled on the notebook. I never use it, so I doubt it, but you may have a point.

Ben, just reporting what I saw. Are you saying TCP/IP is a lightweight protocol? Compared to what?

Robin

By: Ben

Ben — Mon, 19 Nov 2007 23:45:02 +0000

This is uneducated.. The TCP/IP stack takes 2W? Damn dude - good job on having a popular blog - but you should research before you post.

By: Fazal Majid

Fazal Majid — Thu, 15 Nov 2007 23:50:44 +0000

This effect is called Amdahl’s Law. But of course, component manufacturers can’t use balanced system performance as a marketing bullet point.

I suspect the Gigabit Ethernet on your system accounts for a non-negligible proportion of the 13W power draw, probably as muchg as WiFi. You might want to try with the GbE NIC disabled.

By: David Kanter

David Kanter — Thu, 15 Nov 2007 19:02:25 +0000

Robin, most of this is pretty well known. If you look online there are quite a few presentations on where all the power goes - the majority is actually into the display.

One problem that I’d point out is that for notebooks you are generally looking for very small amounts of power - a mW there, 4mW in another system, etc. etc.

The power meter you used is extremely unreliable (I know, I own one and tried to use it for metering server power consumption). To get a meter accurate to the 100th of a watt you’ll really need something else.

2-3W is definitely a pretty big win though.

By: Jonas Lerch

Jonas Lerch — Thu, 15 Nov 2007 18:15:56 +0000

its not about about power, its not about weight and its not about performance.
atm flash based drives does not seem to have that much advantage over normal disks. i think its more about getting rid of the moving parts and that is a good idea for a notebook. the disk in the ipod was one of the major reasons for me to not get one….

By: Robin Harris

Robin Harris — Thu, 15 Nov 2007 17:54:38 +0000

Steve, the OS X system preferences allow you to choose the behavior of better performance or better battery life. If you go to the options you can control screen dimming times, disk standby behavior and such. They aren’t very refined but they did give the basis for 2 CPU measurements noted in the table.

Robin

By: Steve Shockley

Steve Shockley — Thu, 15 Nov 2007 15:07:30 +0000

Interesting, but not really that surprising. When laptops are plugged in they go into “full power” mode where they keep the CPU speed higher for longer and turn off the screen and disk later (if at all).

A more interesting test would be to test on battery, and use runtime as your measurement. If possible, try to do something similar to a normal workload. Even a synthetic disk test (read and write all over the disk) comparing flash vs. magnetic would be useful.