Monday August 02, 2004

The nuances of poolbind

poolbind(1M) allows an authorized user to change the resource pool binding of a zone, project, task or process. However, what does this actually mean? As you might imagine, it means different things for the different pool-bindable entities. Here's a quick explanatory note that should help eliminate any confusion.

The main point to note is this: any changes realized through poolbind(1M) are temporal in nature and will only affect the set of processes identified as belonging to the target process collective at that point in time. By this I mean that no permanent configuration is changed.

For processes and tasks, this is a moot point since there is no way (currently) to specify that either a task or a process is associated with a resource pool. I can't really think of any reason why you would ever want such fine-grained resource management that you would want to have a configuration that specified this relationship; so this is unlikely to ever change.

If you want to permanently change the binding of a project or zone to a resource pool then you must edit the configuration (favourite editor for /etc/project(4) or zonecfg(1M) for a zone). If you want the change to take place immediately, rather than the next time you boot your OS, then you must also use poolbind(1M) to execute the temporal change immediately.

So what actually happens when you use poolbind(1M) to modify the binding of a resource pool bind-able entity?
process The process stops consuming the resources associated with its existing resource pool and begins consuming the resources associated with the new resource pool. Any new processes which fork(2) from this process are also bound to the new resource pool.
task All processes which belong to the task stop consuming the resources associated with their existing resource pool and begin consuming the resources associated with the new resource pool. Any new processes which fork(2) from one of these processes are also bound to the new resource pool.
project All processes which belong to the project stop consuming the resources associated with their existing resource pool and begin consuming the resources associated with the new resource pool. Any new processes which fork(2) from one of these processes are also bound to the new resource pool. However, new processes which join the project after this operation completes will still be associated with the configured resource pool.
zone All processes which belong to the zone stop consuming the resources associated with their existing resource pool and begin consuming the resources associated with the new resource pool. Any new processes which fork(2) from one of these processes are also bound to the new resource pool. Re-booting the zone will restore the configured resource pool binding.

poolbind(1M) is a very powerful workload managment command, especially when applied to a process collective such as a zone or a project. I'll return to the subject of poolbind(1M) later and give some examples of how it can be used to manage workloads quickly and flexibly when problems occur.

(2004-08-02 04:41:30.0) Permalink Comments [6]