Re: [systemd-devel] Reducing unmount/mount of partitions on soft-reboot
On Mi, 13.03.24 16:57, Aditya Gupta (adit...@linux.ibm.com) wrote: > Hello, > > I tried systemd-soft-reboot on a RHEL system, and it's amazing in terms > of it's ability to do a userspace reboot, within fraction of time of a > full system reboot. For example, for a Power system taking around 50 > seconds to do a normal reboot, it took around 4-5 seconds for a > systemd-soft-reboot. > > I have a question on further optimisation. After soft-reboot, I notice > much of the time is taken up by .device and .mount services. This was my > observation based on 'systemd-analyze blame'. Please do let me know if > I am seeing the wrong numbers, or if there's a better way to know. > > Is there some way to 'pass-through' these mounts ? That is, I might not > need to unmount and remount my boot/root paritions. Bind mount the relevant mounts from the current system into /run/nextroot/ if you are using that. If you are not using /run/nextroot/ then you can also define the mount via a .mount unit (rather letting it be auto-generated via /etc/fstab + systemd-fstab-generator), and then set DefaultDependencies=no in it, so that it does not get an implicit Conflicts= dependency on umount.target. This is briefly documented on the systemd-soft-reboot.service man page btw. Lennart -- Lennart Poettering, Berlin
Re: [systemd-devel] Reducing unmount/mount of partitions on soft-reboot
On 13/03/24 18:09, Luca Boccassi wrote: On Wed, 13 Mar 2024 at 12:30, Aditya Gupta wrote: Hello, I tried systemd-soft-reboot on a RHEL system, and it's amazing in terms of it's ability to do a userspace reboot, within fraction of time of a full system reboot. For example, for a Power system taking around 50 seconds to do a normal reboot, it took around 4-5 seconds for a systemd-soft-reboot. I have a question on further optimisation. After soft-reboot, I notice much of the time is taken up by .device and .mount services. This was my observation based on 'systemd-analyze blame'. Please do let me know if I am seeing the wrong numbers, or if there's a better way to know. Is there some way to 'pass-through' these mounts ? That is, I might not need to unmount and remount my boot/root paritions. I tried finding this in available documentation, sorry if I missed it. I did find this ability to 'pass-through' resources/file descriptors/sockets to next boot, by modifying the service files, but don't know how and if I can do a similar thing with mounts. Pre-prepare the additional mounts in /run/nextroot/, after preparing the new rootfs, so that they are ready ahead of time. Thanks for the idea Luca Boccassi ! Makes sense. Guess it's supported in this way then. Thanks, - Aditya Gupta
Re: [systemd-devel] Reducing unmount/mount of partitions on soft-reboot
On Wed, 13 Mar 2024 at 12:30, Aditya Gupta wrote: > > Hello, > > I tried systemd-soft-reboot on a RHEL system, and it's amazing in terms > of it's ability to do a userspace reboot, within fraction of time of a > full system reboot. For example, for a Power system taking around 50 > seconds to do a normal reboot, it took around 4-5 seconds for a > systemd-soft-reboot. > > I have a question on further optimisation. After soft-reboot, I notice > much of the time is taken up by .device and .mount services. This was my > observation based on 'systemd-analyze blame'. Please do let me know if > I am seeing the wrong numbers, or if there's a better way to know. > > Is there some way to 'pass-through' these mounts ? That is, I might not > need to unmount and remount my boot/root paritions. > > I tried finding this in available documentation, sorry if I missed it. I > did find this ability to 'pass-through' resources/file > descriptors/sockets to next boot, by modifying the service files, but > don't know how and if I can do a similar thing with mounts. Pre-prepare the additional mounts in /run/nextroot/, after preparing the new rootfs, so that they are ready ahead of time.
[systemd-devel] Reducing unmount/mount of partitions on soft-reboot
Hello, I tried systemd-soft-reboot on a RHEL system, and it's amazing in terms of it's ability to do a userspace reboot, within fraction of time of a full system reboot. For example, for a Power system taking around 50 seconds to do a normal reboot, it took around 4-5 seconds for a systemd-soft-reboot. I have a question on further optimisation. After soft-reboot, I notice much of the time is taken up by .device and .mount services. This was my observation based on 'systemd-analyze blame'. Please do let me know if I am seeing the wrong numbers, or if there's a better way to know. Is there some way to 'pass-through' these mounts ? That is, I might not need to unmount and remount my boot/root paritions. I tried finding this in available documentation, sorry if I missed it. I did find this ability to 'pass-through' resources/file descriptors/sockets to next boot, by modifying the service files, but don't know how and if I can do a similar thing with mounts. Thanks, Aditya Gupta
