[poky] [PATCH 0/3][RFC] Poky disk space size optimization

[Tian, Kevin]

>From: Saul Wold
>Sent: Tuesday, December 07, 2010 10:47 AM
>
>On 12/06/2010 04:50 PM, Dongxiao Xu wrote:
>> This RFC aims to reduce the poky disk space size.
>>
>> The optimization point is the duplicated file copies in WORKDIR and
>> sysroot directories. When installing, files will be copied from source
>> code package into the image folder; Then some files will be copied
>> from image folder to sysroot-destdir, and some other files will be
>> copied from image folder to package folder. While doing package split,
>> some files will be copied from package folder to packages-split folder,
>> etc.
>>
>There are a couple of concerns with this method, which may lead to
>problems, first is that using links and modifying permissions, it's
>possible that depending on the usage the permissions might be set
>differently.  This will could lead to a second problem: psuedo. It's
>unclear at this point how psuedo will handle this.
>
>I am sure you have been doing testing, just not sure of corner cases.
>
>I know we accepted the first change for the package split link to the
>deploy area, that one made sense as it was package level, this is file
>level and may have hidden problems.

I also agree with Saul here. There do have some difference among those directories
for their own purpose, which finally result in some difference. For example, there're 
different tweaks on libtool and pkgconfig files between sysroot and packaging. That's
why 'image' is copied to package and then sysroot-destdir, and then do necessary
tweaks independently. Here if you want to hard link image to sysroot-destdir, you
need make sure it done after the copy from image to package. Or else you'll end up
to have problem there.

But if you can make sure that given a copy path you're modifying, the
source and the destination are exactly same, and no other path refers to
the source directory, perhaps it's fine to do hard link.

Thanks
Kevin

>
>I am sure that Richard will correct me and add his comments as he
>recovers from his travels.
>
>Sau!
>
>> The thought is to use hard link to replace the direct copy.
>> The three commits do the work of:
>>
>> a) package.bbclass: hard link "image-->sysroot-destdir"
>> b) sstate.bbclass:  hard link "package-->packages-split"
>> c) staging.bbclass: hard link "sysroot-destdir-->sysroots".
>>
>> After testing with minimal/sato/sdk build, this approach could save
>> about 20% disk space.
>> (minimal: 23G ->  19G, sato: 44G ->  35G, sdk: 54G ->  44G).
>>
>> Pull URL: git://git.pokylinux.org/poky-contrib.git
>>    Branch: dxu4/perf
>>    Browse: http://git.pokylinux.org/cgit.cgi/poky-contrib/log/?h=dxu4/perf
>>
>> Thanks,
>>      Dongxiao Xu<dongxiao.xu at intel.com>
>> ---
>>
>>
>> Dongxiao Xu (3):
>>    package.bbclass: Use hard link for package split instead of copy
>>    sstate.bbclass: Use hard link when staging files into sysroots
>>    staging.bbclass: use hardlink when staging files to sysroot-destdir
>>
>>   meta/classes/package.bbclass |    8 +++++---
>>   meta/classes/sstate.bbclass  |    2 +-
>>   meta/classes/staging.bbclass |   27 ++++++++++++++++++++++++++-
>>   meta/lib/oe/path.py          |   28 ++++++++++++++++++++++++++++
>>   4 files changed, 60 insertions(+), 5 deletions(-)
>>
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