Performance optimism
dagfinn | 01 September, 2008 14:02
I like weird ideas. There should be more of them. And the idea that we need to make programs efficient to save energy is weird enough to interest me.
David Peterson tells his version of Rasmus Lerdorfs views on it:
He continues on by stating that PHP developers really need to think about performance for not only scalability reasons but for green reasons. If programs were more efficient it would cut the number of data centres and would reduce energy needs as a result. In our newly emerging age of energy awareness this does become an important aspect and I am glad that he is raising awareness.
Well, theoretically, using less of anything makes good environmental sense. But you have to consider which actions have a big impact and which are marginal. For example, Norwegian politicians have considered banning incandescent light bulbs. But the idea makes a lot less sense here than in some other countries, since it's hardly ever dark and warm at the same time this far north. Therefore, the heat generated by indoor lighting contributes to heating that would be needed anyway and is usually electric already.
"Premature optimization is the root of all evil." It occurs to me that energy saving is a kind of optimization and subject to similar considerations. It needs to be focused so it's applied where it matters most and where you can get the most out of the least effort.
How much traffic does a web app need to have to make optimization worthwhile? Does the green angle add anything to that assessment?
Theoretically, it might if the cost of energy does not cover the cost of its environmental consequences. But it's a question that requires analysis. If cutting data center energy consumption is important, it makes sense to know and apply the strategies that are most cost-effective. Putting the waste heat to use? Using more of the hardware and techniques that are used to make laptops energy-efficient? I don't know, I'm not an expert on these things. What I do know is the idea of green optimization needs that kind of thinking to put it in context.
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Re: Performance optimism
dagfinn | 01/09/2008, 22:20
It (obviously) depends on several factors, but heating typically takes more energy than lighting. The point is that when heating is required, it matters less that most of the energy from incandescent lighting never generates any light, since (nearly all) the energy that generates heat instead of light is useful.
Light Bulbs
Alex Mace | 02/09/2008, 01:06
I would be surprised if the 50 extra watts needed by a single incandescent bulb would not heat your house more efficiently going through your heating system than. Not to mention the costs of getting the replacement bulbs to you, given the higher failure rate of incandescent bulbs.
Optimization follows the law of diminishing returns. The first bit is usually easy. Just turning on a cache for any static content in your site doesn't take much time and provides a substantial performance benefit, so you might as well do it early on because the cost is small. Same for light bulbs - the cost to change them all to florescent is small considering it could cut the cost of lighting your home by 90%. If I knew a programmer who ignored that level of saving in processing time then I'd think him a pretty poor programmer. I'd think the same thing though if it were the other round; spending weeks and weeks getting a tiny improvement before doing the easy things, or doing neither because the hard part would be hard.
green development
Ivo | 02/09/2008, 01:16
The problem I have with the 'good performance leads to green websites' is that in the argument only the raw website performance is considered.
A framework, while costing some performance at runtime, will save a lot of time, and thus energy, at development time. So indeed, you have to calculate the trade-off between these two. (and it's not just about the environment but also about plain cost).
related problems with Rasmus' argument
Koen | 02/09/2008, 02:10
There's another problem related to this. Rasmus apparently said that PHP can't be made fast (reason: scripting language), you would need something like C for that. So I guess that if global heating is such a concern for PHP developers, the environment would be better off if we all turned to C for web development.
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Re: Performance optimism
David Rodger | 01/09/2008, 20:42
What proportion of the total heating would the heat from incandescent light bulbs be, and, if that heat source were removed, would it make much difference to the perceived temperature of the rooms lit that way but also heated by means whose primary purpose is providing heat?