Messages in this thread | | | Date | Sun, 22 Apr 2018 22:52:08 +0200 | From | Pavel Machek <> | Subject | Re: How to disable Linux kernel self-extraction (KERNEL GZIP, KERNEL BZIP2, … )? |
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Hi!
> >>I try to decrease boot time, and my system has an SSD and enough space, so > >>loading 18 instead of 12 MB doesn’t make a difference, but the > >>self-extraction is noticeable. So, I like to disable it. > > > >How long does GZIP extraction take on your hardware? > > It’s hard to measure – at least I didn’t find a way to do so –, but counting > from the last GRUB message to the first message of Linux (with `quiet` > removed from the the command line), it takes roughly *two* seconds. > > ``` > $ ls -l /boot/vmlinuz-4.15.0-3-686-pae > -rw-r--r-- 1 root root 3987200 Apr 19 12:13 /boot/vmlinuz-4.15.0-3-686-pae > $ ls -lh /boot/vmlinuz-4.15.0-3-686-pae > -rw-r--r-- 1 root root 3,9M Apr 19 12:13 /boot/vmlinuz-4.15.0-3-686-pae > $ time scripts/extract-vmlinux vmlinuz-4.15.0-3-686-pae > bla.txt > > real 0m1,204s > user 0m1,041s > sys 0m0,245s > ```
Interesting; looks like I have faster machine (thinkpad X220).
pavel@duo:/data/l/linux$ time scripts/extract-vmlinux /tmp/vmlinux.bin > /tmp/delme 0.21user 0.15system 0.66 (0m0.660s) elapsed 56.36%CPU pavel@duo:/data/l/linux$ ls -al /tmp/delme -rw-r--r-- 1 pavel pavel 18275356 Apr 22 22:44 /tmp/delme pavel@duo:/data/l/linux$ gzip /tmp/delme pavel@duo:/data/l/linux$ time gzip -d /tmp/delme.gz 0.21user 0.02system 0.23 (0m0.232s) elapsed 100.03%CPU pavel@duo:/data/l/linux$ gzip -1 /tmp/delme pavel@duo:/data/l/linux$ time gzip -d /tmp/delme.gz 0.22user 0.03system 0.25 (0m0.257s) elapsed 100.11%CPU pavel@duo:/data/l/linux$ time gzip -d /tmp/delme.gz
..and it also looks like extract-kernel is significantly slower than gzip -9, because it is not using all the CPU. Strange.
Interesting. I somehow assumed gzip -d would be faster than that on modern machines.
So yes, looks like uncompressed kernel image may be good idea. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html [unhandled content-type:application/pgp-signature] | |