Hi,

On Tue, 2017-11-07 at 19:41 +0100, Matthias Fischer wrote:
> Hi,
> 
> On 07.11.2017 16:05, Michael Tremer wrote:
> > Hi,
> > 
> > maybe this function helps:
> > 
> > https://git.ipfire.org/?p=ipfire-2.x.git;a=commitdiff;h=5190eea24f9822a63dc5d06d214b48f973b14f29
> 
> Thanks. I'll take a look...
> 
> > On Tue, 2017-11-07 at 10:46 +0000, Michael Tremer wrote:
> > > On Mon, 2017-11-06 at 22:09 +0100, Matthias Fischer wrote:
> > > ...
> > > > 
> > > > I forgot: Tuning the XZ-parameters... ;-)
> > > 
> > > Good that you are bringing this up. So I think what we should do here is
> > > bringing back XZ compression with -8 so that we do not waste too much space
> > > when
> > > extracting the image again.
> 
> Right now I'm testing how much RAM I need.
> 
> Current 'next'-build is running with:
> 
> 'lfs/cdrom':
> ...
> export XZ_OPT = --threads=0 -8 --memory=500MiB
> ...
> 
> 'lfs/Config':
> ...
> cd /install/packages/package/tmp/ && XZ_OPT="-T0 -8" ...
> ...
> 
> I'm waiting for the results. Takes a while.

You can just run it like this and it will tell you:

[ms(a)hughes ~]$ xz -vv8 -T0
xz: Filter chain: --lzma2=dict=32MiB,lc=3,lp=0,pb=2,mode=normal,nice=64,mf=bt4,depth=0
xz: Using up to 4 threads.
xz: 2,629 MiB of memory is required. The limiter is disabled.
xz: Decompression will need 33 MiB of memory.
xz: Compressed data cannot be written to a terminal
xz: Try `xz --help' for more information.

> > > To not run into memory limits we should detect how much memory the build host
> > > has and set the memory limit to maybe 80% of that. xz will then automatically
> > > scale down to a number of parallel processes that it can fit into memory.
> 
> I'm a bit puzzled about this: I tried using '--memory=70%' as mentioned
> in the xz man pages, but is seems to have no effect. It looks as if the
> percent parameter isn't recognized and ignored. It always ends up in
> "cannot allocate memory". Any hints on this? Do both 'lfs/cdrom' AND
> 'lfs/Config' need the '--memory'-parameter?

Yes, but it would be good to have one place where the parameters are
being generated and then we just use them from a variable.

> > > ...
> > > We will at least need about half a GB which should be a sensible requirement
> > > for a build system any ways.
> 
> Agreed. Because of this I'm testing with '500Mib'.
> 
> > > Will you work on this bringing it into the build system?!
> 
> "I'll do my very best!" :-))

Very well Miss Sophie...

> Best™,
> Matthias