Re: [RFC PATCH 0/4] Add support for LZ4-compressed kernels

["H. Peter Anvin" <hpa@zytor.com>]

On 01/29/2013 02:15 AM, Russell King - ARM Linux wrote:
> On Mon, Jan 28, 2013 at 02:25:10PM -0800, Andrew Morton wrote:
>> What's this "with enabled unaligned memory access" thing?  You mean "if
>> the arch supports CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS"?  If so,
>> that's only x86, which isn't really in the target market for this
>> patch, yes?
>>
>> It's a lot of code for a 50ms boot-time improvement.  Does anyone have
>> any opinions on whether or not the benefits are worth the cost?
>
> Well... when I saw this my immediate reaction was "oh no, yet another
> decompressor for the kernel".  We have five of these things already.
> Do we really need a sixth?
>
> My feeling is that we should have:
> - one decompressor which is the fastest
> - one decompressor for the highest compression ratio
> - one popular decompressor (eg conventional gzip)
>
> And if we have a replacement one for one of these, then it should do
> exactly that: replace it.  I realise that various architectures will
> behave differently, so we should really be looking at numbers across
> several arches.
>
> Otherwise, where do we stop adding new ones?  After we have 6 of these
> (which is after this one).  After 12?  After the 20th?
>

The only concern I have with that is if someone paints themselves into a 
corner and absolutely wants, say, LZO.

Otherwise, per your list it pretty much sounds like we should have lz4, 
gzip, and xz.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.