On Wed, 3 Jul 2013, Kay Sievers wrote: > >> > But that's not my point. It seems pretty easy to make this cgroup > >> > management (in "native mode") a library that can have either a thin > >> > veneer of a main() function, while also being usable by systemd. The > >> > point is to solve all of the problems ONCE. I'm trying to make the > >> > case that systemd itself should be focusing on features and policies > >> > and awesome APIs. > >> > >> You know, getting this all right isn't easy. If you want to do things > >> properly, then you need to propagate attribute changes between the units you > >> manage. You also need something like a scheduler, since a number of > >> controllers can only be configured under certain external conditions (for > >> example: the blkio or devices controller use major/minor parameters for > >> configuring per-device limits. Since major/minor assignments are pretty much > >> unpredictable these days -- and users probably want to configure things with > >> friendly and stable /dev/disk/by-id/* symlinks anyway -- this requires us to > >> wait for devices to show up before we can configure the parameters.) Soo... > >> you need a graph of units, where you can propagate things, and schedule things > >> based on some execution/event queue. And the propagation and scheduling are > >> closely intermingled. > > > > you are confusing policy and mechanisms. > > > > The access to cgroupfs is mechanism. > > > > The propagation of changes, the scheduling of cgroupfs access and > > the correlation to external conditions are policy. > > > > What Tim is asking for is to have a common interface, i.e. a library > > which implements the low level access to the cgroupfs mechanism > > without imposing systemd defined policies to it (It might implement a > > set of common useful policies, but that's a different discussion). > > > > That's definitely not an unreasonable request, because he wants to > > implement his own set of policies which are not necessarily the same > > as those which are implemented by systemd. > > > > You are simply ignoring the fact, that Linux is used in other ways > > than those which you are focussed on. That's true for Google's way to > > manage its gazillion machines and that's equally true for the other > > end of the spectrum which is deep embedded or any other specialized > > use case. Just face it: running Linux on your laptop and on some RHT > > lab machines is covering about 1% of the use cases. > > > > Nevertheless you repeatedly claim, that systemd is the only way to > > deal with system startup and system management, is covering _ALL_ use > > cases and the interfaces you expose are sufficient. > > > > Did you ever work on specialized embedded or big data use cases? I > > really doubt that, but I might be wrong as usual. > > > > So I invite you to prove that you can beat an existing setup for an > > automotive use case with your magic systemd foo. I refund you fully, > > if you can beat the mark of a functional system less than 800ms after > > reset release on a 200MHz ARM machine. Functional is defined by the > > use case requirements and means: > > > > - Basic cgroups management working > > - GUI up and running > > - Main communication interface (CAN bus) up and running > > > > The rest of the system is starting up after that including a more > > complex cgroup management. > > > > According to your claim that systemd is covering everything and some > > more, this should take you a few hours. I grant you a full week to > > work on that. > > > > The use case Tim is talking about is different, but has similar > > constraints which are completely driven by his particular use case > > scenario. I'm sure, that Tim can persuade his management to setup a > > similar contest to prove your expertise on the other extreme of the > > Linux world. > > > > Before answering please think about the relevance of your statements > > "getting this all right isn't easy", "something like a scheduler", > > "users probably want ..." and "stable /dev/disk/by-id/* symlinks" in > > those contexts. > > I don't think anybody needs your money. > > But it's sure an improvement over last time when you wanted to use a > "Kantholz" to make your statement. Now how about the policy vs. mechanisms part of Thomas' e-mail? -- Jiri Kosina SUSE Labs _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
