multi-core image decompression

basharx · 03-23-2020, 05:08 AM

Just wondering if it's possible in principle to speed up the initial kernel image decompression by using multiple CPU cores, which would be useful on older multi-core system; if some rudimentary multi-core control is available at boot time.

I've only found someone comparing general decompression speeds and preferring very fast lz4 decompression (at the expense of image size) as opposed to bz2, xz, lzma, etc. (the use-case was some consumer electronics). Thanks for any insights.

dugan · 03-23-2020, 10:02 PM

Is this for LILO? Just add the "compact" option to lilo.conf. The wait for the image to decompress will disappear.

LuckyCyborg · 03-24-2020, 12:44 AM

Quote:

Originally Posted by dugan

Is this for LILO? Just add the "compact" option to lilo.conf. The wait for the image to decompress will disappear.

That "compact" option affects the loading of kernel and initrd from disk - the step when LILO draws points.

The decompression stage (about which the OP talks) is after this step.

However, the multi-core thing on LILO is doubtfully, considering that LILO is a 16 bit program no different of old good MS-DOS applications, and it runs in real mode, or something similar.

pan64 · 03-24-2020, 01:58 AM

I can't recall, but probably only one core is available that time (at the early phase of the boot).
From the other hand you can check pigz for example here, and you will see an interesting note:

Quote:

Note that decompression is not actually parallelised by pigz (apparently it can’t be), but separate threads are created for different functions of decompression.