[Fedora-livecd-list] [PATCH 6/7] anaconda: liveinst.sh: support turboLiveInst/genMinInstDelta

[Douglas McClendon]

Douglas McClendon wrote:
> Jeremy Katz wrote:
>> On Mon, 2007-09-17 at 22:31 -0500, Douglas McClendon wrote:
>>> Jeremy Katz wrote:
> 
>>> The danger would be loop117, as that is the one created at install 
>>> time.   loop118 being locked up at initramfs time.
>>
>> Not if new anaconda is used with old livecd-creator -- then loop118
>> wouldn't have been used and something else could use it while the live
>> system is running.
> 
> This is true, albeit unlikely as well.  But also fixable by addressing 
> the hardcoded loop device issue across the board.
> 
>>
>>> The reason why I think it should stay as is, instead of setting 
>>> everything up at initramfs time, is because the loop117 gets 
>>> associated with the decompressed-into-devshm contents of loop118.  
>>> The decompression being 7kb->1.2M in the typical case.
>>>
>>> I'd say that the 1.2M ram hit should only be taken during install, 
>>> and that outweighs the benefits of moving the complexity from 
>>> liveinst.sh to initramfs.
>>
>> But the time that the memory hit matters the _most_ is during the
>> install as we have to have swap disabled during parts of it. 
> 
> Obviously this is your call, and from my perspective not a big deal 
> either way.  My own personal preference still remains freeing up the 
> 1.2M of ram during all times other than the install, at the expense of 
> the complexity being in anaconda/liveinst.sh, versus being in initramfs.
> 
> Perhaps by F9 I'll find a mechanism to achieve this that you like...

Or maybe in significantly less time than that...

How's this-

1) In initramfs, instead of lazy unmounting the squashfs, bindmount it 
to /sysroot/mnt/.LiveOS/squashfs

2) store osmin 'uncompressed' on the squashfs

3) in initramfs, set up the osimg-min device, but now with the loop118 
pointing at /sysroot/mnt/.LiveOS/squashfs/osmin

The result- All the same low-impact that the current method has with 
anaconda, but the 1.2M of ram will only get used when anaconda actually 
starts touching /dev/mapper/live-osimg-min

And given that it is a 1.2M file that compresses to 7kb, I'm assuming 
that squashfs will basically read and uncompress it only once.  (and if 
memory is so constrained that during installation it gets swapped out, 
it's probably a good thing that that is possible and squashfs may read 
and uncompress it again).

By jeeves, I think we've got it.  (correct me if I'm wrong or missing 
something)

Thanks for being so stubborn :)

-dmc


>  Otherwise,
>> swap is available and can be used.  It also means that there's less need
>> to worry about the cleanup case in anaconda.  Also, it takes care of my
>> biggest complaint from the past (anaconda having to know too many
>> details of how things are setup -- I _really_ like that right now,
>> anaconda just needs to know to look at block device that's already set
>> up and nothing more is needed)
>>
>> Patch ends up being the attached plus the teensy change so that anaconda
>> will check /dev/mapper/live-osimg-min
> 
> Looks fine to me.  Thanks for the merge work.
> 
> Now I'll move on to seeing what I can do in the next couple days with 
> that persistence patch.  And maybe some other interesting things after 
> that... ;)
> 
> peace...
> 
> -dmc
> 
> P.S.- I'm still curious on that davej ping regarding unionfs.
> 
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