On Thu, Jun 27, 2013 at 11:14 AM, Serge Hallyn <serge.hallyn@xxxxxxxxxx> wrote: > Quoting Tejun Heo (tj@xxxxxxxxxx): >> Hello, Serge. >> >> On Thu, Jun 27, 2013 at 08:22:06AM -0500, Serge Hallyn wrote: >> > At some point (probably soon) we might want to talk about a standard API >> > for these things. However I think it will have to come in the form of >> > a standard library, which knows to either send requests over dbus to >> > systemd, or over /dev/cgroup sock to the manager. >> >> Yeah, eventually, I think we'll have a standardized way to configure >> resource distribution in the system. Maybe we'll agree on a >> standardized dbus protocol or there will be library, I don't know; >> however, whatever form it may be in, it abstraction level should be >> way higher than that of direct cgroupfs access. It's way too low >> level and very easy to end up in a complete nonsense configuration. >> >> e.g. enabling "cpu" on a cgroup whlie leaving other cgroups alone >> wouldn't enable fair scheduling on that cgroup but drastically reduce >> the amount of cpu share it gets as it now gets treated as single >> entity competing with all tasks at the parent level. > > Right. I *think* this can be offered as a daemon which sits as the > sole consumer of my agent's API, and offers a higher level "do what I > want" API. But designing that API is going to be interesting. This is something we have, partially, and are working to be able to open-source. We have a LOT of experience feeding into the semantics that actually make users happy. Today it leverages split-hierarchies, but that is not required in the generic case (only if you want to offer the semantics we do). It explicitly delegates some aspects of sub-cgroup control to users, but that could go away if your lowest-level agency can handle it. > I should find a good, up-to-date summary of the current behaviors of > each controller so I can talk more intelligently about it. (I'll > start by looking at the kernel Documentation/cgroups, but don't > feel too confident that they'll be uptodate :) > >> At the moment, I'm not sure what the eventual abstraction would look >> like. systemd is extending its basic constructs by adding slices and >> scopes and it does make sense to integrate the general organization of >> the system (services, user sessions, VMs and so on) with resource >> management. Given some time, I'm hoping we'll be able to come up with >> and agree on some common constructs so that each workload can indicate >> its resource requirements in a unified way. >> >> That said, I really think we should experiment for a while before >> trying to settle down on things. We've now just started exploring how >> system-wide resource managment can be made widely available to systems >> without requiring extremely specialized hand-crafted configurations >> and I'm pretty sure we're getting and gonna get quite a few details >> wrong, so I don't think it'd be a good idea to try to agree on things >> right now. As far as such integration goes, I think it's time to play >> with things and observe the results. > > Right, I'm not attached to my toy implementation at all - except for > the ability, in some fashion, to have nested agents which don't have > cgroupfs access but talk to another agent to get the job done. > > -serge -- To unsubscribe from this list: send the line "unsubscribe cgroups" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
