Re: [Tails-dev] Slower boot on experimental branch

Hi,

intrigeri wrote (10 Aug 2014 18:18:13 GMT) :
> TL;DR: could you please retry with an ISO built from current
> experimental, with the default compression options?

Not needed anymore, I did tests on 3 different bare metal machines,
in addition to my previous ones in KVM + some more I've received.
See the last comments on #7706 for details.

So, my conclusions are:

* I confirm sajolida's findings: the more compressed SquashFS, if
badly ordered, increases boot time from USB on bare metal by 36 to
55%, depending on the machine. We don't want that.

* Compressing the SquashFS more *and* reordering the SquashFS, in the
worst case (from USB, slow machine), makes the boot take 8% more
time; in the best case (from DVD, fast machine), it makes it 45%
faster.

Current experimental branch implements both: compressing the SquashFS
more, and reordering it. I'd like to see this land into 1.2, if not in
1.1.1:

* The slightly slower boot in some cases seems acceptable to me, once
we balance it with shorter download time, more space for IUKs on
the system partition, and the fact that it (temporarily)
workarounds the problems caused by #7462.

* The faster boot in some other cases is of course great.

So, I'm asking for a review and merge of feature/7705-smaller-squashfs
for 1.1.1, and, if deemed too risky despite the benefits (#7462...),
for 1.2 instead.

Note that the way we order the SquashFS is optimized for booting from
DVD, on the machine used to profile the boot (that is, in my case,
a fast one). We could possibly optimize it for booting from USB, if we
think that it's a more common usecase nowadays, or one that we want to
better support. Thoughts?

Cheers,
--
intrigeri