4.15.0-34だとinitramfsの解凍に10分以上かかってたことが判明。うむむー。
[ 0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.15.0-34-generic root=UUID=a6268849-42cb-4d0e-80f3-eb2704407c01 ro vga=normal
:
[ 1.565894] Unpacking initramfs...
[ 360.051261] perf: interrupt took too long (2536 > 2500), lowering kernel.perf_event_max_sample_rate to 78750
[ 480.021383] perf: interrupt took too long (3222 > 3170), lowering kernel.perf_event_max_sample_rate to 62000
[ 616.739081] Freeing initrd memory: 55196K
4.4上で解凍してみると一瞬
$ uname -srm
Linux 4.4.0-135-generic x86_64
$ time cpio -id < /boot/initrd.img-4.15.0-34-generic
56 blocks
real 0m0.014s
user 0m0.004s
sys 0m0.008s
もちろん4.4のinitrdも。
$ time cpio -id < /boot/initrd.img-4.4.0-135-generic
56 blocks
real 0m0.025s
user 0m0.000s
sys 0m0.016s
4.15.0-34に起動してみた。cpioでの解凍は一瞬。やっぱり起動時のみの問題だね。
$ uname -srm
Linux 4.15.0-34-generic x86_64
$ dmesg | grep -A1 initramfs
[ 1.529762] Unpacking initramfs...
[ 360.052064] perf: interrupt took too long (2507 > 2500), lowering kernel.perf_event_max_sample_rate to 79750
$ time cpio -id < /boot/initrd.img-4.4.0-135-generic
56 blocks
real 0m0.053s
user 0m0.021s
sys 0m0.016s
$time cpio -id < /boot/initrd.img-4.15.0-34-generic
56 blocks
real 0m0.054s
user 0m0.022s
sys 0m0.014s
4.15.0-36が来てたので起動してみたんだけどやっぱり遅い。
$ uname -srm
Linux 4.15.0-36-generic x86_64
$ dmesg | grep -A1 initramfs
[ 1.675430] Unpacking initramfs...
[ 350.053271] perf: interrupt took too long (2513 > 2500), lowering kernel.perf_event_max_sample_rate to 79500