Why it's so hard to understand?
Posted May 27, 2010 7:28 UTC (Thu) by khim
In reply to: The road forward for systemd
Parent article: The road forward for systemd
I've had this discussion so many times and I still can't believe people are thinking like that. Guys, OR and XOR are different operations! Please open the logic textbook and read about difference between them! This is vital if you want to talk about systemd!
Either implicit dependencies are used, and you rely on socket activation, but you don't start daemons as early as they could be
This perfect illustration: systemd can do A or B, ok, but since if you do A (but don't do B) you need to do this and if you do B (but not do A) you need to do that - and you so are doing neither this nor that so how can that work? Of course in reality systemd can do "A (activate service via socket) or B (start services from the list) and that means it can do A and B simultaneously! Terrific, uber-uncomprehensible idea, isn't it? Implicit dependencies are used and you start daemons as early as possible (i.e.: you start all daemons in parallel). If daemon A needs deamon B it does not mean daemon B should be started earlier - it means daemon A will start first and then will wait for daemon B activation. This will start the system in fastest time possible.
It's all explained in original paper. I know, I know, majority of population can not even imagine OR operation and only think about XOR (they call it OR, of course) - but these people shouldn't discuss design of systemd, that's all.
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