Bootlin's Best Techniques For A Smaller Kernel + Faster Boot Times

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  • phoronix
    Administrator
    • Jan 2007
    • 67366

    Bootlin's Best Techniques For A Smaller Kernel + Faster Boot Times

    Phoronix: Bootlin's Best Techniques For A Smaller Kernel + Faster Boot Times

    In addition to a talk at the Embedded Linux Conference Europe on trimming the Linux boot time with systemd changes, Michael Opdenacker of embedded Linux engineering firm Bootlin presented on their techniques for not only speeding up the Linux boot time but also reductions in the kernel image size...

    Phoronix, Linux Hardware Reviews, Linux hardware benchmarks, Linux server benchmarks, Linux benchmarking, Desktop Linux, Linux performance, Open Source graphics, Linux How To, Ubuntu benchmarks, Ubuntu hardware, Phoronix Test Suite
  • milkylainen
    Senior Member
    • Mar 2012
    • 1106

    #2
    I see a lot of oddball choices there.

    Comment

    • Slithery
      Senior Member
      • Sep 2017
      • 151

      #3
      One low-hanging fruit I can still see is the initramfs, I don't have one...

      Comment

      • stormcrow
        Senior Member
        • Jul 2017
        • 1517

        #4
        Originally posted by Slithery View Post
        One low-hanging fruit I can still see is the initramfs, I don't have one...
        Not needed at all if all the drivers needed to mount the root FS are included in the monolithic part of the kernel. I'd suspect a lot of single use devices using full scale GP CPUs would have monolithic kernels and initramfs would be superfluous. Initramfs is more to allow for easier genericization (made up word) for software meant to run on many different hardware platforms not under a central plan and control like a desktop distribution for the public.

        Comment

        • R41N3R
          Senior Member
          • Jul 2017
          • 1113

          #5
          Originally posted by Slithery View Post
          One low-hanging fruit I can still see is the initramfs, I don't have one...
          I'm not aware that this is possible... How did you do this? Is this something like direct kernel boot in a VM?

          Edit: I see, you probably have compiled a own kernel that includes file system support to mount root directly.

          I do have slow boot times because of UEFI on all my systems. UEFI wastes 50% to 70% of my boot time.
          Last edited by R41N3R; 03 November 2019, 12:25 PM.

          Comment

          • Ananace
            Phoronix Member
            • Feb 2016
            • 118

            #6
            It's really nice that people are having fun with Linux boot, though I can't say that I'm very bothered by it myself.

            Since I run LUKS, 90% of the boot time is spent typing in the password and unlocking the disk, so it's not really worth it to micro-optimize the other parts of boot.
            Though systemd-bootchart has been great in showing what useless things your distro have decided to put into the lower-level boot targets - or just enabled by default - that really don't need to be there.

            Comment

            • caligula
              Senior Member
              • Jan 2014
              • 3342

              #7
              Originally posted by Ananace View Post
              It's really nice that people are having fun with Linux boot, though I can't say that I'm very bothered by it myself.

              Since I run LUKS, 90% of the boot time is spent typing in the password and unlocking the disk, so it's not really worth it to micro-optimize the other parts of boot.
              Though systemd-bootchart has been great in showing what useless things your distro have decided to put into the lower-level boot targets - or just enabled by default - that really don't need to be there.
              Exactly. It takes days to start up or shut down the Large Hadron Collider. Why would anyone care about boot times faster than 2 weeks? As a self-centered person I can't really comprehend why others might have different opinions of various stuff.

              Comment

              • milkylainen
                Senior Member
                • Mar 2012
                • 1106

                #8
                Originally posted by Ananace View Post
                It's really nice that people are having fun with Linux boot, though I can't say that I'm very bothered by it myself.

                Since I run LUKS, 90% of the boot time is spent typing in the password and unlocking the disk, so it's not really worth it to micro-optimize the other parts of boot.
                Though systemd-bootchart has been great in showing what useless things your distro have decided to put into the lower-level boot targets - or just enabled by default - that really don't need to be there.
                I don't think the article was meant as a insight into desktop stuff. This is relevant to the embedded world. They are a world apart from your desktop needs.

                Comment

                • Ananace
                  Phoronix Member
                  • Feb 2016
                  • 118

                  #9
                  Originally posted by milkylainen View Post

                  I don't think the article was meant as a insight into desktop stuff. This is relevant to the embedded world. They are a world apart from your desktop needs.
                  Oh most definitely, but it's still really nice to see that people are having fun with the boot process. While much of what they do doesn't apply onto desktops, I can't imagine that desktop boot will be negatively impacted by any of this work.
                  For the majority of the people reading these articles though, I'm just adding a few anecdotes for things that they personally might see that can affect their boot times too.

                  It is worth mentioning that a few of the tweaks shown here are quite viable even for desktops or laptops though, even if userspace tends to be the much larger time-waster there.

                  Comment

                  • AsuMagic
                    Senior Member
                    • Apr 2016
                    • 573

                    #10
                    Dunno about you all but I would kind of mind waiting 2 minutes for my car to boot up after I stalled the engine :^)

                    Comment

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