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

Russell King - ARM Linux linux at arm.linux.org.uk
Tue Jan 29 05:15:49 EST 2013


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?



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