Raspberry distcc/crossdev or chroot what is faster

dasPaul

I have a perfect gentoo running Raspberry Pi 2. For emerge I used distcc to my desktop PC which worked quite good.
Would emerge be faster if I mount the RPi card to my desktop Pc and qemu/chroot into it and doing emerge ?

NeddySeagoon · Posted: Thu Jul 07, 2016 7:50 pm Post subject:

dasPaul,

The qemu/chroot option is slow as the host CPU has to emulate the target CPU in sottware.
I tried with SPARC. A 3.4GHz Phenom II got me a 200MHz SPARC. The real hardware is 400MHz.

The SD card is very slow. I have everything except boot on a USB HDD.
NFS works too.
On the Pi, all the IO except the SD card is via a single USB2 port, so USB beats NFS as you don't have network latency but there is not a lot in it.

Pure cross compiling is good where it works. Then install the binaries on the Pi.
Next is cross distcc.
Building natively on the Pi is probably faster than a qemu/chroot but I've not benchmarked the Pi2 case.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

dasPaul · Posted: Fri Jul 08, 2016 7:01 am Post subject:

That's just what I was thinking. I will move root to USB-HDD and add another Desktop to cross/distcc.
Thanks!

chithanh · Posted: Fri Jul 08, 2016 4:27 pm Post subject:

You can export the rpi root filesystem over NFS to a fast computer (ensure portage tree and PORTAGE_TMPDIR are local) as NeddySeagoon suggested.
Then you can emerge in qemu-user chroot while your RPi is running.

dasPaul · Posted: Sat Jul 09, 2016 5:16 pm Post subject:

@chithanh, but as NeddySeagoon told qemu emulation is painfull slow and my recent test with a rootfs copy and chrooting, doing emerge took longer than doing distcc on the real RPi system.