Booting Linux In Just One Second

[monraaf]

There aren't many modern distros that care about RAM usage and boot speed. Solus boots in 1.089 seconds, it is using latest GNOME technologies an it is built from scratch. Linux distros can be modern and beautiful but light and fast at the same time.

[SystemCrasher]

Hell yeah, fast booting in embedded could be quite an important topic: users tend to hate to wait for device start up and if startup time is slow, you'll face a very unpleasant comments about device performance. And in some tasks it just plain unacceptable to have slow boot.

So far, actual "high-score" is something like a mere 300 milliseconds, booting straight into Qt application. Achieved by some guys few years ago, using Ti OMAP (and Ti's on-chip ROM is attrubuted to most of these 300ms). Yet it is very specific setup, where they used init=/their/program, making their system virtually single-tasked

...as for LZO: my benchmarks indicate LZ4 beats LZO at decompression speed any day. In some cases it can be like 2x faster (which is epic, because LZO is already fast). Though LZ4 tends to compress a bit worse than LZO, but difference is usually insignificant. Yet it actually a matter of hitting a sweet point between decompression speed and compression ratio, trying to reach some point where (read time + decompress time) is minimal. This thing depends heavily on actual storage. Sometimes storage is fast, and decompression time dominates. Sometimes storage so shamefully slow, it can be okay to take heavier compression algo, and reduce of read pays for itself, even if decompression is a bit slower. These days, Linux kernel supports LZ4 compression "out of the box" for virtually everything (in sense you can choose it in menuconfig and build system would call lz4 program to compress kernel and would craft adequate "self-extracting" stub, same for initrd and other stuff).

And on my PC, system would boot in <5 seconds from ssd, but it's not like if I can do much about 10 seconds delay due to BIOS crap on the way. OTOH, most of ARMs (Raspberry Pi excluded, thanks to Broadcom/videocore!) can be conviced to kick my u-boot really fast. In most extreme setup, SPL pre-loader of u-boot can kick kernel at fixed place directly, taking time only to init RAM and read kernel to RAM and nothing else. Yeah, Intel, FUCK OFF with proprietary UEFI crap.

[Uqbar]

First, as stated by someone else earlier, Linux boot doesn't include hardware initialization. Which can be (and usually is) pretty longer than the OS boot time. It's like your super car going from 0 to 100 Mph in 2 seconds, but it needs one week of checks and preparation before that!

Second, embedded devices are not PCs. They usually get on once and work for weeks, months or even years without being turned off. While still important, boot time is less important than stability by far.

Third, a 1/2 second boot time in an embedded device can be a double-edged blade. Instead of fixing a memory leak or some other stability issue, someone could be tempted to place a watchdog to trigger a reboot. Of course, you would keep your 99.999% up-time by doing so, but in a really scary way: by hiding the dust under the carpet.

Fourth, "user perception" is bullshit. Users would like to see a PC, a router or even a server up and running as fast as a portable MP3 player or a microwave oven. That can hardly be the case. And most users don't "perceive" that because of lack of knowledge and of will to understand. Yes, users pay and keep the market up and running. But most of us are little more than typing apes.

So, IMHO, fast boot time is nice. But not as nice as a 730 days up-time without a glitch after a 1 minute boot.

[Kano]

I really would like to see more ppl working on this, I got a VANTAGE VT-Zapper lately and this SAT receiver needs about 17 s from hot standby. Cold Boot is was much longer - this shows even for consumer electronics fast Linux boot is needed - you could think the device is dead if you need to wait 60+ s. It can be done but it needs time/money to do so. Booting a fast PC with SSD and a tiny DM with a simple DM without GRUB (directly with UEFI embedded Bootmanager) is not hard compared to that.

[Ardje]

I get about 5 seconds from typing reboot to being able to log in again, if I use at most a boot delay of 1s for uboot. Ubuntu 14.04 cleaned and without ramdisk, and emmc as storage.
IP static configured, and I am actually using ipv6 mostly. Another 5 to show the POS app.

[Ardje]

I really would like to see more ppl working on this, I got a VANTAGE VT-Zapper lately and this SAT receiver needs about 17 s from hot standby.

I think it should not take 17s... So I assume something is off with the network settings or it does weird things.
I have a vu+ solo2. From standby it's "instant" on, from poweroff to action it does take a while. My samsung TV takes about 5..10 seconds to boot though...

[mmstick]

3-second (to desktop) OS boots are pretty common when using SSDs. The main time drain is the firmware (11 seconds for me!) and idling bootloader.

I have an unfortunate magnetic drive that takes 30-60 seconds just to power on and mount the /home partition. It is such a sad thing as otherwise it boots in 3 seconds with just the SSD.

[Ardje]

Booting in 1 second is not fast and booting in 20 seconds is not slow either. I just want my Linux machine to boot visually faster than the Windows and Mac OS machines around me.

Take a sony videocam (ok, video cameras actually do not exist anymore), press on the power button, and bam, within 1 second it boots into the user interface and is ready for recording.
All done with mmu less kernel at that time. And the fun part is when you realise that the mmu-less tree was maintained by samsung at that time.
Anyway: fast booting linux machines exist for a long time, there is a big need for booting fast, just because booting costs less energy than standby for weeks. But it should be ready to run at that moment.
But the current hardware allows for "full" featured MMU-capable linux environments to boot. Good drivers are also important for fast boots.

[erendorn]

It seems people are missing that this is sub second boot on a single core, 400MHz cpu. Of course booting can be fast on your desktop i5. But everytime I reboot a phone, a modem or a set-top box, it's definitely not in the 2s range.

[erendorn]

First, as stated by someone else earlier, Linux boot doesn't include hardware initialization. Which can be (and usually is) pretty longer than the OS boot time. It's like your super car going from 0 to 100 Mph in 2 seconds, but it needs one week of checks and preparation before that!

Second, embedded devices are not PCs. They usually get on once and work for weeks, months or even years without being turned off. While still important, boot time is less important than stability by far.

Third, a 1/2 second boot time in an embedded device can be a double-edged blade. Instead of fixing a memory leak or some other stability issue, someone could be tempted to place a watchdog to trigger a reboot. Of course, you would keep your 99.999% up-time by doing so, but in a really scary way: by hiding the dust under the carpet.

Fourth, "user perception" is bullshit. Users would like to see a PC, a router or even a server up and running as fast as a portable MP3 player or a microwave oven. That can hardly be the case. And most users don't "perceive" that because of lack of knowledge and of will to understand. Yes, users pay and keep the market up and running. But most of us are little more than typing apes.

So, IMHO, fast boot time is nice. But not as nice as a 730 days up-time without a glitch after a 1 minute boot.

I disagree. You can have embededs in cars, UAVs, backup systems that you want online rapidly... Just because it's not useful for common use cases does not mean it's not usefull at all.
And hardware initialization is not a problem when you are choosing your (embeded) hardware for a fast boot in the first place.
It's like saying "cars are nice, but not as nice as truck, so I don't think cars should exist"