People say python is slow, but UGRD is very fast, even on slow hardware.
Using a rpi3 on powersave:
time dracut --no-compress --force
real 0m56.537s
user 0m41.309s
sys 0m15.989s
time ugrd --no-compress
real 0m6.599s
user 0m3.744s
sys 0m2.147s
ugrd compression is limited by single thread python performance, but still builds faster than dracut which calls zstd:
time dracut --force
real 1m6.812s
user 1m0.391s
sys 0m16.300s
time ugrd
real 0m37.686s
user 0m35.386s
sys 0m2.510s
time dracut --no-compress --force
real 0m7.142s
user 0m3.233s
sys 0m4.811s
time ugrd --no-compress
real 0m0.864s
user 0m0.424s
sys 0m0.583s
time dracut --force
real 0m9.653s
user 0m29.121s
sys 0m5.253s
time ugrd
real 0m13.011s
user 0m12.349s
sys 0m0.643s
Here, dracut is able to run faster by making use of threading with the zstd utility, python xz currently does not thread python/cpython#114954
ugrd makes very small images, even with no compression, it creates smaller images than dracut with zstd compression!
| Generator | Compression | Size | Mode |
|---|---|---|---|
| dracut | none | 30M | hostonly |
| dracut | none | 24M | standard |
| dracut | zstd | 13M | standard |
| ugrd | none | 9.41M | hostonly |
| dracut | zstd | 8.5M | hostonly |
| ugrd | xz (default) | 2.64M | hostonly |
| Generator | Compression | Size | Mode |
|---|---|---|---|
| dracut | none | 392M | standard |
| dracut | none | 192M | hostonly |
| dracut | zstd | 91M | standard |
| ugrd | none | 65.36M | hostonly |
| dracut | zstd | 49M | hostonly |
| ugrd | xz (default) | 18.89M | hostonly |
For this image, luks, gpg, and yubikey modules are required, greatly increasing the image size
ugrd boots faster than dracut, even without udev:
Dracut boot:
[ 3.106933] recovery
[ 3.106939] with environment:
[ 3.106945] HOME=/
[ 3.106951] TERM=linux
[ 3.142999] mmc0: host does not support reading read-only switch, assuming write-enable
[ 3.149037] mmc0: Host Software Queue enabled
[ 3.150788] mmc0: new high speed SDHC card at address aaaa
[ 3.154389] mmcblk0: mmc0:aaaa SL16G 14.8 GiB
[ 3.164336] mmcblk0: p1 p2
[ 3.166987] mmcblk0: mmc0:aaaa SL16G 14.8 GiB (quirks 0x00004000)
[ 3.174279] mmc1: new high speed SDIO card at address 0001
[ 3.177061] usb 1-1: new high-speed USB device number 2 using dwc_otg
[ 3.178984] Indeed it is in host mode hprt0 = 00001101
[ 3.385637] usb 1-1: New USB device found, idVendor=0424, idProduct=9514, bcdDevice= 2.00
[ 3.389174] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 3.392006] hub 1-1:1.0: USB hub found
[ 3.394109] hub 1-1:1.0: 5 ports detected
[ 3.554215] dracut: Gentoo-2.17
[ 3.690010] usb 1-1.1: new high-speed USB device number 3 using dwc_otg
[ 3.792071] usb 1-1.1: New USB device found, idVendor=0424, idProduct=ec00, bcdDevice= 2.00
[ 3.795715] usb 1-1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 3.800751] smsc95xx v2.0.0
[ 3.906640] SMSC LAN8700 usb-001:003:01: attached PHY driver (mii_bus:phy_addr=usb-001:003:01, irq=184)
[ 3.911722] smsc95xx 1-1.1:1.0 eth0: register 'smsc95xx' at usb-3f980000.usb-1.1, smsc95xx USB 2.0 Ethernet, b8:27:eb:0c:d0:4b
[ 5.151361] EXT4-fs (mmcblk0p2): mounted filesystem 3b614a3f-4a65-4480-876a-8a998e01ac9b ro with ordered data mode. Quota mode: none.
[ 5.286768] EXT4-fs (mmcblk0p2): unmounting filesystem 3b614a3f-4a65-4480-876a-8a998e01ac9b.
[ 5.337578] dracut: Checking ext4: /dev/mmcblk0p2
[ 5.340808] dracut: issuing e2fsck -a /dev/mmcblk0p2
[ 5.373619] dracut: rootfs: clean, 247841/908960 files, 815408/3757440 blocks
[ 5.389944] dracut: Mounting /dev/mmcblk0p2 with -o defaults
[ 5.466096] EXT4-fs (mmcblk0p2): mounted filesystem 3b614a3f-4a65-4480-876a-8a998e01ac9b r/w with ordered data mode. Quota mode: none.
[ 5.562939] dracut: Mounted root filesystem /dev/mmcblk0p2
[ 5.900654] dracut: Switching root
ugrd boot:
[ 3.106379] Freeing unused kernel memory: 4864K
[ 3.108254] Run /init as init process
[ 3.109895] with arguments:
[ 3.109902] /init
[ 3.109909] recovery
[ 3.109915] with environment:
[ 3.109921] HOME=/
[ 3.109927] TERM=linux
[ 3.144962] mmc0: host does not support reading read-only switch, assuming write-enable
[ 3.150951] mmc0: Host Software Queue enabled
[ 3.152676] mmc0: new high speed SDHC card at address aaaa
[ 3.156096] mmcblk0: mmc0:aaaa SL16G 14.8 GiB
[ 3.165547] mmc1: new high speed SDIO card at address 0001
[ 3.168096] mmcblk0: p1 p2
[ 3.170596] mmcblk0: mmc0:aaaa SL16G 14.8 GiB (quirks 0x00004000)
[ 3.177101] usb 1-1: new high-speed USB device number 2 using dwc_otg
[ 3.179132] Indeed it is in host mode hprt0 = 00001101
[ 3.385638] usb 1-1: New USB device found, idVendor=0424, idProduct=9514, bcdDevice= 2.00
[ 3.389224] usb 1-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 3.392200] hub 1-1:1.0: USB hub found
[ 3.394433] hub 1-1:1.0: 5 ports detected
[ 3.685123] usb 1-1.1: new high-speed USB device number 3 using dwc_otg
[ 3.793618] usb 1-1.1: New USB device found, idVendor=0424, idProduct=ec00, bcdDevice= 2.00
[ 3.797330] usb 1-1.1: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[ 3.802269] smsc95xx v2.0.0
[ 3.899272] SMSC LAN8700 usb-001:003:01: attached PHY driver (mii_bus:phy_addr=usb-001:003:01, irq=184)
[ 3.904286] smsc95xx 1-1.1:1.0 eth0: register 'smsc95xx' at usb-3f980000.usb-1.1, smsc95xx USB 2.0 Ethernet, b8:27:eb:0c:d0:4b
[ 4.427679] EXT4-fs (mmcblk0p2): mounted filesystem 3b614a3f-4a65-4480-876a-8a998e01ac9b ro with ordered data mode. Quota mode: none.
[ 4.544220] EXT4-fs (mmcblk0p2): unmounting filesystem 3b614a3f-4a65-4480-876a-8a998e01ac9b.
[ 4.687024] EXT4-fs (mmcblk0p2): mounted filesystem 3b614a3f-4a65-4480-876a-8a998e01ac9b ro with ordered data mode. Quota mode: none.
[ 4.813752] UGRD completed
Multiple tests were performed, boot timed did not deviate by more than half a second Tests where undervoltages were reported were ignored, but none were detected in ugrd runs