New Fair Share (FSS) and Fixed (FX) Schedulers

The FSS and FX schedulers are new user process schedulers. Both schedulers use the same range of priorities (0 to 59) as the time sharing (TS)/interactive (IA) scheduling classes.

FX is a fixed-priority scheduler that gives processes that run in it an assured priority. FX is not meant to be a default scheduler. TS balances loads. FX does not. You can run FX and TS on the same system, but if you set the priority too high for FX, you could starve the processes that run in TS.

The FSS guarantees application performance by explicitly allocating shares of CPU resources to projects. Additional advantages of the FSS are as follows:

• Allows the fine-grained sharing of CPU resources on a system.

• Controls the allocation of available CPU resources among workloads based on their importance. Their importance is expressed by the number of shares of CPU resources that you assign to each workload.

FSS should not be used with TS or FX on the same system unless processor sets are used. If you use processor sets, you can mix TS, IA, and FX with FSS in one system as long as all the processes that run on each processor set are in one scheduling class to prevent them from competing for the same CPUs. The FX scheduler, in particular, should not be used in conjunction with the new FSS scheduling class unless processor sets are used, to prevent applications in the FX class from using priorities that are high enough to starve applications in the FSS class.

The following table identifies where to get more information about using these schedulers and other Solaris resource management features, such as projects and tasks, to better manage system resources.