On Wed, Nov 14, 2012 at 04:05:12PM +0000, Roger Leigh wrote: > On Wed, Nov 14, 2012 at 03:04:35PM +0100, John Paul Adrian Glaubitz wrote: > > On Wed, Nov 14, 2012 at 09:49:07PM +0800, Patrick Lauer wrote: > > > But anyway, we're getting tired of their ADHD-driven changes just to > > > change things > > TBH, I'm getting tired of people who are constantly shooting against > > them because these people are unwilling to accept changes. We're not > > bringing Linux forward if we stick to 30-year-old concepts. systemd is a good > > design and most people actually agree otherwise it wouldn't become > > standard on so many distributions (except Ubuntu, but that's rather a > > political decision IMHO). > systemd does have some good design features. It also has some bad > ones. It's not as black and white as some people have claimed. > If you want a reliable system, you need a reliable PID 1. Putting > additional complexity into PID1 increases the likelihood that a > bug will bring down your *entire system*. PID 1 is a single point > of failure. It *must* be absolutely dependable and reliable. > Upstart is also AFAIK at fault here. [Citation needed] Upstart provides a PID 1 that is absolutely rock solid. It's true that it's more complex than sysvinit, because it's more featureful; but great care has been taken to only pull the features into PID 1 that absolutely have to be there, and the implementation of those features is very elegant and maintainable.[1] Aside from libc, upstart has only two external library dependencies (three in trunk), dbus and nih: $ objdump -p /sbin/init | grep NEEDED NEEDED libnih.so.1 NEEDED libnih-dbus.so.1 NEEDED libdbus-1.so.3 NEEDED librt.so.1 NEEDED libc.so.6 $ And upstart is rigorously unit-tested at build time. That's a far cry from systemd's 8 external dependencies: $ objdump -p /lib/systemd/systemd | grep NEEDED NEEDED libselinux.so.1 NEEDED libdbus-1.so.3 NEEDED libudev.so.0 NEEDED libwrap.so.0 NEEDED libpam.so.0 NEEDED libaudit.so.0 NEEDED libcap.so.2 NEEDED libkmod.so.2 NEEDED librt.so.1 NEEDED libc.so.6 NEEDED ld-linux.so.2 $ And of all the concerns raised when Ubuntu (and Fedora and OpenSuSE) switched to upstart, "PID 1 is buggy and crashes" was not one of them. > sysvinit is fairly minimal, but even it could be simplified > further. Other init systems (e.g. s6)[1] take that even further > so that at any point in time, PID1 is running an image dedicated > to the current system state, e.g. booting, running, shutting down, > and it will exec() a new image to initiate a state change. When > running normally, PID 1 should do nothing except to reap zombies, > and switch to shutdown. Everything else can be done in a > separate process started by PID 1. This is an arbitrary design constraint that's not grounded in anyone's actual experience of deploying upstart. This is not theoretical. upstart has been PID 1 in Ubuntu since 2006. It *is* absolutely dependable and reliable. -- Steve Langasek Give me a lever long enough and a Free OS Debian Developer to set it on, and I can move the world. Ubuntu Developer http://www.debian.org/ slangasek@ubuntu.com vorlon@debian.org [1] http://ifdeflinux.blogspot.co.uk/2012/11/upstart-cookbook-updated-for-developers.html
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