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LWN.net Weekly Edition for May 23, 2013
An "enum" for Python 3
An unexpected perf feature
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A look at the PyPy 2.0 release
Will it make it faster or slower?
Posted Sep 6, 2009 17:59 UTC (Sun) by josh (subscriber, #17465)
Given appropriate optimization, booting should take a lot less time than un-hibernating. In particular, the latter takes more time the more RAM you have in use.
In any case, many good reasons still exist to turn a laptop off rather than hibernating or suspending.
Posted Sep 6, 2009 18:56 UTC (Sun) by jreiser (subscriber, #11027)
Yes. There is still mainstream hardware (PC clone 1 to 3 years old) that does not suspend and hibernate properly. Also, coming out of hibernation is slower than booting on many desktop and laptop systems, including several that I use regularly.
boot speed matters
Posted Sep 6, 2009 19:44 UTC (Sun) by DonDiego (subscriber, #24141)
Posted Sep 6, 2009 21:58 UTC (Sun) by drag (subscriber, #31333)
The most classic example of this that I can think of is automobile radios. They maintain power continuously in order to maintain the internal memory of radio station selects. If you remove the battery from the car or let the car run out of battery capacity (so you'd need a "jump" to get started) then you would have to go and reprogram your radio.
Another classic example is that older non-solid-state radios and televisions would have to maintain the temperatures on their tubes in order to start up quicker. I had a old tube television that doubled as a nice space heater. When plugged in it would take a few seconds to start up. However if it was cold then it may take up to a view minutes for the image to fully stabilize on the screen.
More modern examples of this are things like HD TV sets that take long to do a cold boot. Also VCRs would often suck more electricity shutoff then when they were operating.
In fact I would not be surprised that most modern appliances use current while "shut off". Not that I have done a survey.
The thing that sucks about Linux here is that power management is still unreliable. Its unreliable in the sense that it is not consistent and it causes crashes and dataloss occasionally.
If everything was right and proper in the world when you go to shut of your computer there should only be one option
And that will send it into low power mode. No shutoff, reboot, suspend, hibernate, or anything like that. To get to those options you should have to dig further because there is no reason to use those during normal operations.
It should suspend AND save a system image to swap. That way when you start it up again then your golden.. even if you remove the battery the system can recover from the memory image in your storage. But Linux is not there yet, so we still need a half a dozen different options. This way no matter the expectations of the user it will more then likely do the right thing.
If Linux was reliable then there would be no hesitation for people to close the lid and stick it in the bag.
There are Linux systems that do this sort of thing correctly. Linux cell phones are one. The e-paper tables like Amazon's go into standby in between each screen render. My Dell Mini9 works like a champ now (I still wait and look for the power light to pulsate (indicating suspend) before sticking it in a bag though).
Posted Sep 6, 2009 22:17 UTC (Sun) by dlang (✭ supporter ✭, #313)
some people want their computer to actually shut off, so that they can use the power in the battery later when they turn it on rather than have it drain away in 'suspend mode'
the 'standby only' mode may be what you consider ideal, but many other people would not find it ideal, even if there were no bugs in the linux suspend
Posted Sep 7, 2009 0:01 UTC (Mon) by foom (subscriber, #14868)
It's certainly possible some people want that, but I doubt there's _very many_ that go weeks
between uses of their laptop, on battery.
If linux power management worked as well on all the multitude of supported laptops/desktops, as
Apple has done for their 10 or so models, this conversation wouldn't be happening. Everyone I
know with a mac laptop simply closes the lid when they're done using it, no question. It's nearly
100% reliable and uses extremely minimal power.
Posted Sep 7, 2009 0:22 UTC (Mon) by dlang (✭ supporter ✭, #313)
it's not necessarily that people want to wait weeks between times that they use their computers, but if a battery will last a week on standby, letting the system sit in standby mode uses 1/7 of your power, that's a significant amount if you aren't going to be near a power outlet.
don't get me wrong, it's not that I don't want to see improvements in linux power management, it's just that I don't see 'suspend' replacing 'off' as being either realistic or desirable for all cases.
Posted Sep 7, 2009 3:22 UTC (Mon) by daniels (subscriber, #16193)
boot speed and standby power waste
Posted Sep 7, 2009 4:55 UTC (Mon) by eru (subscriber, #2753)
Yes, they do. And a lot. Plugging them into a power meter is eye-opening. For example a few years old Dell desktop PC I tested consumes 9 watts while supposedly "off", and my DTV set-top box seems to draw about the same amount, whether it is nominally "on" or "off". Google for "standby power waste" for more complaints...
With CO2 reduction being the hot issue, authorities have started to look into this. EU and some other legislators have already set standby power limits that will gradually come into effect.
A few years on, only consumer devices that are draw practically no current at all when "off" will be seen acceptable. For Linux to live on then, it either has to boot fast, or be reliably able to suspend into non-volatile memory.
Posted Sep 7, 2009 11:02 UTC (Mon) by email@example.com (guest, #38022)
Posted Sep 7, 2009 22:11 UTC (Mon) by ignacio.hernandez (subscriber, #56157)
Posted Sep 8, 2009 8:24 UTC (Tue) by drag (subscriber, #31333)
Posted Sep 8, 2009 20:26 UTC (Tue) by njs (guest, #40338)
Not that this is terribly relevant to anything.
Posted Sep 8, 2009 16:22 UTC (Tue) by HenrikH (guest, #31152)
Posted Sep 7, 2009 6:03 UTC (Mon) by jmm82 (guest, #59425)
I would not be surprised if Debian did not care about boot time given my earlier logic. Most people who care about boot time will probably be using Ubuntu or a similar distro.
Posted Sep 10, 2009 7:36 UTC (Thu) by PaulWay (✭ supporter ✭, #45600)
The real value of upstart is that it also handles the hibernate and suspend processes. Instead of having separate, semi-magical scripts to handle the suspend process, upstart uses the same scripts as it would if it were shutting down whatever needs to be shut down. That way you know that everything's shut down cleanly and the developer hasn't patched a bug in one place and not in another.
In fact, you can extend this to most state transitions. Turn the wifi and bluetooth off to save power or to work in an airplane? Upstart will do the same things as required if you were shutting down the whole laptop. Shut down the USB devices to save power? Same thing. You get to use the same scripts all the way through, meaning everything is much more robust. And those start-ups start everything up in parallel, just like your boot sequence.
So upstart is great for speed and flexibility whether you suspend, hibernate, shut down, or whatever.
Posted Sep 10, 2009 16:37 UTC (Thu) by Quazatron (guest, #4368)
Is boot speed really important?
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