Kernel compile time....?

[Lorian]

Anyone give me a clue how long a kernel compile takes roughly (raspbian?). Running on a Pi, overclocked to 850/500 on a type 10 card?
Been going for about an hour so far, do I have time for 2 pints?

I'm thinking easily...

[Lorian]

Well in the end 5h 17m

I don't think it would slow down much on a slower SD card as the process is very CPU bound.

The board didn't get unduly warm during the build.

You need about 2.5Gb of disk (SD) space to complete the build.

[naicheben]

Class 6 SD-Card : more than 2 pints !

I started at 10pm and let it run over night. Next time I will start the compilation with:
"time make" to see how long it took. But at least it is obvious that you get drunk before the comilation is finished

[ian.macarthur123]

As an aside, I doubt the class of the SD card is making that much of a difference, since it looks very much as if the the way the SD interface is being clocked in the R-Pi is set to a fixed (and relatively low) clock speed.
So installing a faster card probably is not affecting access times all that much.

Though if anyone had actual metrics that prove I'm wrong, I'd be delighted!

[fjen]

As an aside, I doubt the class of the SD card is making that much of a difference, since it looks very much as if the the way the SD interface is being clocked in the R-Pi is set to a fixed (and relatively low) clock speed.

The SD card clockspeed can be set with init_emmc_clock in config.txt, see http://elinux.org/RPi_config.txt#Boot_options

[Lorian]

I installed and configured ccache and my pi-based kernel build this morning only took an hour.

bviously the first run after installin ccache takes a little longer than normal while it does its caching.

[bob_binz]

Can't you cross-compile on your PC?

[Lorian]

There is no fun in that

[bob_binz]

There is no fun in that

Heh, true enough - but if you find yourself building the kernel often (as I did recently trying to keep my wifi module in sync with the firmware updates!) it becomes a bind waiting over night all the time! I must say I'm not familiar with ccache though.

[Lorian]

Its worth installing even on your PC build env. apt-get install ccache

The full kernel build is using < 100Mb for the cache. Takes seconds to set up.

[spennig]

There may not be fun in cross-compiling, but it takes under 3 minutes on a reasonably modern multi-cored machine. Well worth it if you keep upto date with git.

[raspip]

time (make && make modules)
real 640m0.838s
user 595m59.250s
sys 27m34.970s

[hippy]

Building for whatever comes with Jessie on a Pi B+ at 900MHz, just the kernel make ( default with the addition of DisplayPort ), modules and the rest yet to come ...

Real 987m31.008s
User 901m34.060s
Sys 37m2.700s

So basically 17 hours.

[PeterO]

Just as an update to this...

Kernel build on a PI3 with external USB hard disk takes 61 minutes, but needed some extra cooling from a desk fan to keep the "high temp" warning icon at bay.

PeterO