On Fri, Jul 13, 2012 at 11:19 AM, Andrea Adami <andrea.adami@gmail.com> wrote:

On Fri, Jul 13, 2012 at 8:45 AM, Koen Kooi <koen@dominion.thruhere.net> wrote:
>
> Op 12 jul. 2012, om 21:22 heeft Saul Wold het volgende geschreven:
>
>> On 07/12/2012 11:58 AM, Koen Kooi wrote:
>>> Any volunteers to test this on a system with >4 real cores?
>>>
>>
>> Koen,
>>
>> Does OE-Core or Poky have an image setup for using .xz by default?
>
> No, and as you can see from Andrei's patches, it would have never worked :)
>
> regards,
>
> Koen
>

This leads to a similar remark for lzma:

The xz/lzma have been added with commit 38334ac and at that time both
where using XZ_COMPRESSION_LEVEL.

The code has been refactored afterwards and what happened is that lzma
now defaults to compression 7 (the default) while xz is way too high
(default is 6).

Nope. It's default value is -9.

There is a well hidden pitfall with that, being that any image,
including the initramfs, will use that compression factor.

As you can notice in that (old) man xz [2] the memory requirements

What old version?

are very high and what did happen to me was that the cpio.lzma could
not be decompressed thus kernel could not boot (we override now the
value setting "-e2" in our BSP).

Without threads, memory demand was around 700mb. So it should be ok for most of machines.

Adding more threads will multiply that figures.

Indeed. With 8GB memory at my disposal i couldn't compress an image with -e -9 and -T 0 (-T 4)/