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SN
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Re: Time from Standing Start to Services Running

Tue Mar 06, 2012 11:05 pm

To anyone who's had one of these beasties in their grubby mits, whats the typical time (in seconds one hopes) from applying a goodly 5v to the power socket to having Linux up and running and jobs in the rcX.d directories running?

As noted elsewhere I'm looking at a vehicular solution and clearly I can't sit on my drive waiting too long for grub, kernel code, device drivers and various other gubbins to start up before I'm ready to roll
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jmg123
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Re: Time from Standing Start to Services Running

Tue Mar 06, 2012 11:21 pm

I can't tell you how fast it is, as I don't have one yet, but I'd imagine that getting to boot time as small as possible will be popular for a number of people/applications. These things might help:


Customise the kernel to remove everything that is not needed
boot with the minimum amount of modules possible, and don't use modprobe
use a read only filesystem (squashfs is good)
disable the console.

Maybe there should be a "leaderboard" for fastest boot times? along with the config used to get that time.

Lynbarn
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Re: Time from Standing Start to Services Running

Tue Mar 06, 2012 11:25 pm

By the time you've been round and kicked the tyres, and done the daily checks we all do, you should be good to go!

Actually, you may well be able to get away with leaving it on overnight, which would also keep the clock set correctly.

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SN
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Re: Time from Standing Start to Services Running

Tue Mar 06, 2012 11:52 pm

jmg123 said:


Maybe there should be a "leaderboard" for fastest boot times? along with the config used to get that time.


This, I like - a sort of Top Gear Fastest Lap in an Extra-Ordinary Priced Linux Box
Steve N – binatone mk4->intellivision->zx81->spectrum->cbm64->cpc6128->520stfm->pc->raspi ?

CookieMonster
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 12:11 am

SN said:


To anyone who"s had one of these beasties in their grubby mits, whats the typical time (in seconds one hopes) from applying a goodly 5v to the power socket to having Linux up and running and jobs in the rcX.d directories running?

As noted elsewhere I"m looking at a vehicular solution and clearly I can"t sit on my drive waiting too long for grub, kernel code, device drivers and various other gubbins to start up before I"m ready to roll


About 90 seconds. Unless something gets optimized from videos posted during the holidays.

But, it may be possible to enter some sort of low power suspend mode that will allow fast wake up but not draw too much power. Clever ideas will come after hands get the boards.

vroomfondel
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 3:39 am

Some reading material while we are waiting for our RPis

_http://elinux.org/Boot_Time

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SN
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 12:14 pm

this is what we should be shooting for!

http://www.makelinux.com/emb/f.....tboot/omap
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nick.mccloud
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 12:30 pm

SN said:


As noted elsewhere I"m looking at a vehicular solution and clearly I can"t sit on my drive waiting too long for grub, kernel code, device drivers and various other gubbins to start up before I"m ready to roll


No RTC so you will have to leave it on all the time so time = 0s

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nick.mccloud
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 12:31 pm

However, your car battery will be flat from keeping it running overnight so time = infinite!

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SN
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 9:33 pm

. . . Not if I get the 2nd battery fitted. On the subject of RTC, if you had a GPS mouse attached via USB, I assume it would be straightfoward to read UTC time off the mouse when it became available.
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Caliber Mengsk
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 10:04 pm

O-o a second lead acid battery in the car? If it were drained regularly, that would kill the alternator sooooooo fast. I'd just get this http://www.sparkfun.com/products/99 and use the GPIO pins to get the time when needed. Assuming you could figure that out. (by that, I mean the GPIO pin programming and interfacing an I2C connection through them. I don't know what libraries are already out for the rPi.)

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nick.mccloud
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 10:25 pm

SN said:


On the subject of RTC, if you had a GPS mouse attached via USB, I assume it would be straightfoward to read UTC time off the mouse when it became available.


For what values of straightforward.

setTimeFromMyUSB_GPS_device(please);

Ah, yes, turns out it's straightforward. No USB/serial programming or decoding of NMEA strings or nuffink.

CookieMonster
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 10:37 pm

nmcc said:


However, your car battery will be flat from keeping it running overnight so time = infinite!


Perhaps on your side of the pond a car battery sucks cheezits, but over here a typical auto battery (they do vary by size) is say 800 to 1200 watt hours. To keep a good lifetime one should not draw it below 50% too often. So 400-600 usuable watt hours.

The Pi is to draw under 1A at 5v = 5w. A car battery should power a Pi for ~100 hours and still be at 50%. Overnight should not be a problem.

CookieMonster
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 10:40 pm

Caliber Mengsk said:


O-o a second lead acid battery in the car? If it were drained regularly, that would kill the alternator sooooooo fast. I"d just get this http://www.sparkfun.com/products/99 and use the GPIO pins to get the time when needed. Assuming you could figure that out. (by that, I mean the GPIO pin programming and interfacing an I2C connection through them. I don't know what libraries are already out for the rPi.)


You must get your alternators wher nmcc gets his batteries.

If you really have some electrical draw, get a for-real alternator and a smart charge controller. But, really, a nice LiPo pack to keep the Pi up overnight (or a week or more if sleep can be implemented) will not be a heavy draw to recharge.

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SN
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 10:56 pm

And my first battery is a 15v whopper seeing as it needs to turn over a Land Rover V6 Diesel. There are standard fit second batteries which are happy to run an Engel beer fridge (ahem) and other essential eqipment for a few days without issue anyway, so a few hundred milliwatts would not create much of an issue
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Rek
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Re: Time from Standing Start to Services Running

Wed Mar 07, 2012 11:26 pm

"The Pi is to draw under 1A at 5v = 5w. A car battery should power a Pi for ~100 hours and still be at 50%. Overnight should not be a problem."

It pulls well under 1 amp running full blast. I expect less than 1 watt when it"s idle. http://www.raspberrypi.org/archives/260
11+2=1101

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