YARN-7533. Documentation for absolute resource support in Capacity Scheduler. Contributed by Sunil G.
diff --git a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/CapacityScheduler.md b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/CapacityScheduler.md
index 4754c94..2f49c6b 100644
--- a/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/CapacityScheduler.md
+++ b/hadoop-yarn-project/hadoop-yarn/hadoop-yarn-site/src/site/markdown/CapacityScheduler.md
@@ -64,6 +64,8 @@
* **Priority Scheduling** - This feature allows applications to be submitted and scheduled with different priorities. Higher integer value indicates higher priority for an application. Currently Application priority is supported only for FIFO ordering policy.
+* **Absolute Resource Configuration** - Administrators could specify absolute resources to a queue instead of providing percentage based values. This provides better control for admins to configure required amount of resources for a given queue.
+
Configuration
-------------
@@ -118,14 +120,18 @@
| Property | Description |
|:---- |:---- |
-| `yarn.scheduler.capacity.<queue-path>.capacity` | Queue *capacity* in percentage (%) as a float (e.g. 12.5). The sum of capacities for all queues, at each level, must be equal to 100. Applications in the queue may consume more resources than the queue's capacity if there are free resources, providing elasticity. |
-| `yarn.scheduler.capacity.<queue-path>.maximum-capacity` | Maximum queue capacity in percentage (%) as a float. This limits the *elasticity* for applications in the queue. Defaults to -1 which disables it. |
+| `yarn.scheduler.capacity.<queue-path>.capacity` | Queue *capacity* in percentage (%) as a float (e.g. 12.5) OR as absolute resource queue minimum capacity. The sum of capacities for all queues, at each level, must be equal to 100. However if absolute resource is configured, sum of absolute resources of child queues could be less than it's parent absolute resource capacity. Applications in the queue may consume more resources than the queue's capacity if there are free resources, providing elasticity. |
+| `yarn.scheduler.capacity.<queue-path>.maximum-capacity` | Maximum queue capacity in percentage (%) as a float OR as absolute resource queue maximum capacity. This limits the *elasticity* for applications in the queue. Defaults to -1 which disables it. |
| `yarn.scheduler.capacity.<queue-path>.minimum-user-limit-percent` | Each queue enforces a limit on the percentage of resources allocated to a user at any given time, if there is demand for resources. The user limit can vary between a minimum and maximum value. The former (the minimum value) is set to this property value and the latter (the maximum value) depends on the number of users who have submitted applications. For e.g., suppose the value of this property is 25. If two users have submitted applications to a queue, no single user can use more than 50% of the queue resources. If a third user submits an application, no single user can use more than 33% of the queue resources. With 4 or more users, no user can use more than 25% of the queues resources. A value of 100 implies no user limits are imposed. The default is 100. Value is specified as a integer. |
| `yarn.scheduler.capacity.<queue-path>.user-limit-factor` | The multiple of the queue capacity which can be configured to allow a single user to acquire more resources. By default this is set to 1 which ensures that a single user can never take more than the queue's configured capacity irrespective of how idle the cluster is. Value is specified as a float. |
| `yarn.scheduler.capacity.<queue-path>.maximum-allocation-mb` | The per queue maximum limit of memory to allocate to each container request at the Resource Manager. This setting overrides the cluster configuration `yarn.scheduler.maximum-allocation-mb`. This value must be smaller than or equal to the cluster maximum. |
| `yarn.scheduler.capacity.<queue-path>.maximum-allocation-vcores` | The per queue maximum limit of virtual cores to allocate to each container request at the Resource Manager. This setting overrides the cluster configuration `yarn.scheduler.maximum-allocation-vcores`. This value must be smaller than or equal to the cluster maximum. |
| `yarn.scheduler.capacity.<queue-path>.user-settings.<user-name>.weight` | This floating point value is used when calculating the user limit resource values for users in a queue. This value will weight each user more or less than the other users in the queue. For example, if user A should receive 50% more resources in a queue than users B and C, this property will be set to 1.5 for user A. Users B and C will default to 1.0. |
+ * Resource Allocation using Absolute Resources configuration
+
+ `CapacityScheduler` supports configuration of absolute resources instead of providing Queue *capacity* in percentage. As mentioned in above configuration section for `yarn.scheduler.capacity.<queue-path>.capacity` and `yarn.scheduler.capacity.<queue-path>.max-capacity`, administrator could specify an absolute resource value like `[memory=10240,vcores=12]`. This is a valid configuration which indicates 10GB Memory and 12 VCores.
+
* Running and Pending Application Limits
The `CapacityScheduler` supports the following parameters to control the running and pending applications:
