Messages in this thread | | | Subject | Re: How to disable Linux kernel self-extraction (KERNEL GZIP, KERNEL BZIP2, …)? | From | Paul Menzel <> | Date | Sun, 22 Apr 2018 21:55:51 +0200 |
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Dear Pavel,
Am 22.04.2018 um 12:20 schrieb Pavel Machek: > On Fri 2018-04-20 16:36:00, Paul Menzel wrote:
>> 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 ```
As another data point, my self-built (*bigger*) image with XZ used for compression.
``` $ ls -lh /boot/vmlinuz-4.16.0+ -rw-r--r-- 1 root root 6,1M Apr 14 10:48 /boot/vmlinuz-4.16.0+ $ time /usr/src/linux-headers-4.17.0-rc1+/scripts/extract-vmlinux vmlinuz-4.16.0+ > bla.txt
real 0m2,190s user 0m1,792s sys 0m0,500s ```
So, it’s really noticeable if the rest of the system starts in less then five seconds to a login prompt, or you are trying to achieve to display the LUKS passphrase dialog more or less instantly.
Kind regards,
Paul
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