I was surprised by how much less power mobile devices used than laptops. I knew it was considerably less, but the factor of 30 was more than I would have guessed. I wonder how much more efficient and higher capacity batteries are likely to affect the power consumption of mobile devices. I know that many people are interested in improving batteries, but I don't really know how much progress is being made.
yuel1
@uncreative One other thing to consider in mobile devices is heat dissipation. Unlike desktops and laptops, most mobile devices (with the exception of a few) use passive cooling rather than active cooling (think fans). This severely limits the amount of power mobile device processors can draw, regardless of the battery capacity.
rokislt10
An important thing to remember about heat is that it's more than just an annoyance or will only be an issue if it immediately damages the chip. In addition to decreasing the life of electrical components, heat can also cause these components to become more unstable. This does a good job of explaining why that is:
http://tinyurl.com/nsaz3lv
Berry
It's worth noting that air cooling systems - the ones supplied by default on most cpu's and gpu's are pretty pathetic. Air has such poor heat transmission it is often used as an insulator in double-layer windows. With good liquid/phase change cooling system (which now can go for as little as 200$ for your cpu, gpu and memory) one can run a 3.1 ghz cpu all the way up to 4.0 ghz without inflicting much damage on the cpu or memory granted that it is unlocked. Don't know how the costs scale on large server racks though.
I have a question of whether the problem with increases in power required is mainly the heat output and if so, whether advances in cooling technology will lower the power wall. Of course, optimizing code for power consumption is already a known concern and those curious can read more here: http://rtcmagazine.com/articles/view/102063.
kk
@Corian We also need to take the cost of cooling into account as well. I think existing technology already allows us to make high power processors, but the cost of cooling required would make such processors commercially unviable.
ananyak
I'm curious, why do most modern computers only have 2-4 cores? Don't most people run enough processes (eg. browser tabs, music) that the OS can leverage many more cores. Why don't we have 16 cores running at 500Mhz instead of 4 cores running at 2Ghz. Wouldn't this reduce power consumption?
-___-
@ananyak Most programs nowadays are not parallel friendly.
ananyak
@-__- That's true, but I don't think individual programs need to be parallel friendly. We typically run enough processes that the OS can exploit parallelism simply by scheduling different processes on different cores. For example, if I have 80 processes running, I can schedule 10 on each core, can't I?
-___-
@ananyak If the OS can exploit parallelism this efficient, I think there is no point for us to take 15-418. Also, 500Mhz is too slow even for cell phones to run single process jobs.
evanl
@ananyak I think -__- means that if each core can only run up to 500MHz then non-parallel friendly programs that require more than 500MHz would not be able to run properly. The way browser tabs and windows are handled in Firefox and Chrome are different. Chrome spawns each new tab and window as a new process, while Firefox doesn't. Since you can have as many tabs or windows as you want, Firefox, which is not as parallel friendly as Chrome, will end up putting more stress on a single processor. (Though, you would probably run out of memory first.) Source: Task Manager
zeppelin
The discussion about whether or not programs need to be parallel friendly is becoming more important each day. As performance gains have slowed down almost to a complete halt due to Moore's law and the power wall, multi-core architectures are gaining prevalence, so I believe creating parallel friendly programs will move from a nice addition to a necessary adoption in order to keep up to speed with competition as in the example above mentioning Chrome and Firefox.
I was surprised by how much less power mobile devices used than laptops. I knew it was considerably less, but the factor of 30 was more than I would have guessed. I wonder how much more efficient and higher capacity batteries are likely to affect the power consumption of mobile devices. I know that many people are interested in improving batteries, but I don't really know how much progress is being made.
@uncreative One other thing to consider in mobile devices is heat dissipation. Unlike desktops and laptops, most mobile devices (with the exception of a few) use passive cooling rather than active cooling (think fans). This severely limits the amount of power mobile device processors can draw, regardless of the battery capacity.
An important thing to remember about heat is that it's more than just an annoyance or will only be an issue if it immediately damages the chip. In addition to decreasing the life of electrical components, heat can also cause these components to become more unstable. This does a good job of explaining why that is: http://tinyurl.com/nsaz3lv
It's worth noting that air cooling systems - the ones supplied by default on most cpu's and gpu's are pretty pathetic. Air has such poor heat transmission it is often used as an insulator in double-layer windows. With good liquid/phase change cooling system (which now can go for as little as 200$ for your cpu, gpu and memory) one can run a 3.1 ghz cpu all the way up to 4.0 ghz without inflicting much damage on the cpu or memory granted that it is unlocked. Don't know how the costs scale on large server racks though.
a link describing how google cools its cluster... http://www.datacenterknowledge.com/archives/2012/10/17/how-google-cools-its-armada-of-servers/
@uncreative Battery capacity hasn't really increased much over the years. There's an article here describing some of the battery technologies floating around: http://www.nature.com/news/the-rechargeable-revolution-a-better-battery-1.14815
I have a question of whether the problem with increases in power required is mainly the heat output and if so, whether advances in cooling technology will lower the power wall. Of course, optimizing code for power consumption is already a known concern and those curious can read more here: http://rtcmagazine.com/articles/view/102063.
@Corian We also need to take the cost of cooling into account as well. I think existing technology already allows us to make high power processors, but the cost of cooling required would make such processors commercially unviable.
I'm curious, why do most modern computers only have 2-4 cores? Don't most people run enough processes (eg. browser tabs, music) that the OS can leverage many more cores. Why don't we have 16 cores running at 500Mhz instead of 4 cores running at 2Ghz. Wouldn't this reduce power consumption?
@ananyak Most programs nowadays are not parallel friendly.
@-__- That's true, but I don't think individual programs need to be parallel friendly. We typically run enough processes that the OS can exploit parallelism simply by scheduling different processes on different cores. For example, if I have 80 processes running, I can schedule 10 on each core, can't I?
@ananyak If the OS can exploit parallelism this efficient, I think there is no point for us to take 15-418. Also, 500Mhz is too slow even for cell phones to run single process jobs.
@ananyak I think -__- means that if each core can only run up to 500MHz then non-parallel friendly programs that require more than 500MHz would not be able to run properly. The way browser tabs and windows are handled in Firefox and Chrome are different. Chrome spawns each new tab and window as a new process, while Firefox doesn't. Since you can have as many tabs or windows as you want, Firefox, which is not as parallel friendly as Chrome, will end up putting more stress on a single processor. (Though, you would probably run out of memory first.) Source: Task Manager
The discussion about whether or not programs need to be parallel friendly is becoming more important each day. As performance gains have slowed down almost to a complete halt due to Moore's law and the power wall, multi-core architectures are gaining prevalence, so I believe creating parallel friendly programs will move from a nice addition to a necessary adoption in order to keep up to speed with competition as in the example above mentioning Chrome and Firefox.