[Dev] Setting dash as default shell (or getting rid of bash)

Carsten Haitzler c.haitzler at samsung.com
Tue Oct 1 03:13:41 GMT 2013


i wonder how it figures if its "beneficial" :) hmm "if the first portion 
is not smaller"... this could be a problem with some file formats.. is 
this just "smaller" or "significantly smaller"? eg edj (eet) files have 
a header and directory block - its never compressed for speed of 
lookups, but each data segment in the file may (or may not be) 
compressed via any one of several compression methods (xlib, lz4/lz4hc, 
jpeg for lossy images etc.)... :) it'd be nice to be able to provide 
globs like "do not compress *.edj, *.jpg, *.png ....etc." :)

btw  lz4 or lz4hc might be an awesome addition to the compression algos 
supported. it seems to be "in progress". :)

On 10/01/2013 11:04 AM, MyungJoo Ham wrote:
>
> With BTRFS you may "compress everything forcibly" or "compress if 
> seems beneficial".
>
> You may use "+c" to force compression on a file, but it seems that you 
> cannot foce not to compress.
>
> https://btrfs.wiki.kernel.org/index.php/Compression
>
> Jaehoon (jh80.chung at samsung <mailto:jh80.chung at samsung>) may give more 
> input; he has been experimenting with BTRFS & F2FS for Tizen 2.2.
>
> ------- *Original Message* -------
>
> *Sender* : 하이츨러<c.haitzler at samsung.com> 수석/차세대Computing 
> Lab(S/W센터)/삼성전자
>
> *Date* : 2013-10-01 10:51 (GMT+09:00)
>
> *Title* : Re: [Dev] Setting dash as default shell (or getting rid of bash)
>
> there is? cool. how do you enable compression? is it "compress 
> everything by default" or can you "cmod" or chattr etc. specific files 
> to then indicate to the fs to go compress them... ?
>
> On 10/01/2013 06:20 AM, Barbieri, Gustavo wrote:
>>
>> There is transparent decompression for btrfs including different 
>> methods such as lzo or zlib.
>>
>> --
>>
>> Gustavo Sverzut Barbieri
>>
>> Intel Open source Technology Center
>>
>> *From:*dev-bounces at lists.tizen.org 
>> [mailto:dev-bounces at lists.tizen.org] *On Behalf Of *Carsten Haitzler
>> *Sent:* Sunday, September 29, 2013 11:50 PM
>> *To:* dev at lists.tizen.org
>> *Subject:* Re: [Dev] Setting dash as default shell (or getting rid of 
>> bash)
>>
>> On 09/28/2013 02:33 AM, Thiago Macieira wrote:
>>
>>     On sexta-feira, 27 de setembro de 2013 12:09:17, Leandro Pereira wrote:
>>
>>         If you're concerned about binary size, you could use a binary packer
>>
>>         such as UPX. A quick test here, compressing my own shell (on a x86-64
>>
>>         machine) yields pretty good compression. UPX decompresses really quickly
>>
>>         so it's very unlikely it'll become a bottleneck:
>>
>>       
>>
>>     Binary compression is a trade-off between disk space usage and RAM usage.
>>
>>     Depending on the system, it might also be a security risk.
>>
>>       
>>
>>     That's because the decompressor needs writable pages to decompress the image
>>
>>     to, then mark it as executable. Hopefully, the decompressor moves from RW to
>>
>>     RX instead of RWX, but you need to check that. And in any case, since those
>>
>>     pages aren't backed by actual files on disk, the kernel must use the swap if it
>>
>>     needs to discard the pages, even the unused pages.
>>
>>
>> if anything this would be best done with filesystem native 
>> compression (ala cramfs) and then the pages are at least backed and 
>> shared. :) short-term this only helps if we move to use cramfs, but 
>> longer-term it may be a valid "todo list" item to look at adding 
>> transparent decompression to btrfs/f2fs/ext4 etc.
>>
>>
>>   
>>   
>>
>>
>>
>>
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>>
>>
>>
>> -- 
>> The above message is intended solely for the named addressee and may
>> contain trade secret, industrial technology or privileged and
>> confidential information otherwise protected under applicable law
>> including the Unfair Competition Prevention and Trade Secret Protection
>> Act. Any unauthorized dissemination, distribution, copying or use of the
>> information contained in this communication is strictly prohibited. If
>> you have received this communication in error, please notify the sender
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>
> -- 
> The above message is intended solely for the named addressee and may
> contain trade secret, industrial technology or privileged and
> confidential information otherwise protected under applicable law
> including the Unfair Competition Prevention and Trade Secret Protection
> Act. Any unauthorized dissemination, distribution, copying or use of the
> information contained in this communication is strictly prohibited. If
> you have received this communication in error, please notify the sender
> by email and delete this communication immediately.
>
> --
>
> MyungJoo Ham (함명주), PHD
>
> System S/W Lab, S/W Platform Team, Software Center
> Samsung Electronics
> Cell: +82-10-6714-2858
>

-- 
The above message is intended solely for the named addressee and may
contain trade secret, industrial technology or privileged and
confidential information otherwise protected under applicable law
including the Unfair Competition Prevention and Trade Secret Protection
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information contained in this communication is strictly prohibited. If
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