Adds documentation for configuring Slurm (#324)

* Outlines slurm setup docs

* Fills in outline

docs/install/slurm.md

@@ -1,3 +1,88 @@
 # Configuring Slurm
 
-This documentation is coming soon.
+Keystone is agnostic to most Slurm settings, and requires minimal modification to a running Slurm cluster.
+However, certain fairshare features are incompatible with the Keystone accounting system and must be disabled.
+
+## Enable Resource Tracking
+
+Slurm categorizes system usage in terms of trackable resources (TRES).
+To impose a usage limit on a computational resource, that resource must be represented in Slurm as a TRES.
+Resource tracking for common TRES' like CPU, memory, and energy usage is enabled by default.
+However, administrators may wish to extend the default list to enable limits on additional resource types (e.g., for GPU usage).
+
+The `AccountingStorageTRES` setting is used to extend the default list of TRES values stored in the Slurm database.
+See the official [Surm documentation](https://slurm.schedmd.com/tres.html#conf) on `slurm.conf` settings for details.
+
+??? Example "Example: Tracking GPU usage"
+
+    The following example enables tracking for GPU resources in addition to the default TRES tracked by slurm.
+
+    ```
+    AccountingStorageTRES=gres/gpu
+    ```
+
+??? Example "Example: Tracking GPU and IOP"
+
+    The following example extends the default TRES list with resources called GPU and iop1.
+
+    ```
+    AccountingStorageTRES=gres/gpu,license/iop1
+    ```
+
+## Disable Usage Decay
+
+Slurm defaults to using the [multifactor priority plugin](https://slurm.schedmd.com/priority_multifactor.html) to schedule jobs.
+This can be confirmed by checking the Slurm `PriorityType` setting.
+
+```bash
+scontrol show config | grep PriorityType
+```
+
+When using the multifactor plugin, the `PriorityDecayHalfLife` and `PriorityUsageResetPeriod` settings need to be disabled.
+Leaving either of these features enabled will cause Slurm to periodically reduce an account's recorded resource usage, causing inaccuracies in resource allocation limits. 
+
+```
+PriorityDecayHalfLife=00:00:00
+PriorityUsageResetPeriod=NONE
+```
+
+!!! Important
+
+    Disabling the `PriorityDecayHalfLife` and `PriorityUsageResetPeriod` values may affect your Slurm fairshare policy.
+    Administrators should adjust the rest of their fairshair policy settings as they see appropriate. 
+
+## Configuring Charging Rates
+
+Keystone enforces allocation limits in units of billable TRES.
+The total billable TRES for a given job is determined using the allocated resources in addition to a series of billing weights:
+
+$$ 
+Billable = \sum_{T} \, \left ( W_{T} * A_{T} \right )
+$$
+
+The billing weights are set on a per-partition basis using the `TRESBillingWeights` setting.
+Billing weights are definable in variety of units. 
+See the [Slurm documentation](https://slurm.schedmd.com/tres.html) for more details.
+
+??? Example "Example: Billing for CPU"
+
+    The following example only charges users for CPU resources.
+
+    ```
+    PartitionName=partition_name TRESBillingWeights="CPU=1.0"
+    ```
+
+??? Example "Example: Billing for CPU and GPU"
+
+    The following example charges users for GPU resources at twice the rate of CPU resources.
+
+    ```
+    PartitionName=partition_name TRESBillingWeights="CPU=1.0,GRES/gpu=2.0"
+    ```
+
+To ensure the total allocated resources are calculated correctly, the `MAX_TRES` flag must be enabled. 
+Doing so ensures the billable TRES include individual TRES on a node (e.g. cpus, mem, gres) plus the sum of all global TRES (e.g. licenses).
+
+```
+PriorityFlags=MAX_TRES
+```