From 4ddd58cc5979894bb7243e1183ebe95886da2944 Mon Sep 17 00:00:00 2001
From: Mel Kiyama
Date: Fri, 13 Oct 2017 13:04:03 -0700
Subject: [PATCH] doc: Warning about add cgroup kernel issue to resource group
docs. (#3492)
* doc: Warning about add cgroup kernel issue to resource group docs.
* docs: fix typo
---
gpdb-doc/dita/admin_guide/wlmgmt.xml | 136 +++--
.../admin_guide/workload_mgmt_resgroups.xml | 529 ++++++++++++------
2 files changed, 422 insertions(+), 243 deletions(-)
diff --git a/gpdb-doc/dita/admin_guide/wlmgmt.xml b/gpdb-doc/dita/admin_guide/wlmgmt.xml
index 783d564ca0..41d7d11c5c 100644
--- a/gpdb-doc/dita/admin_guide/wlmgmt.xml
+++ b/gpdb-doc/dita/admin_guide/wlmgmt.xml
@@ -11,71 +11,83 @@
amount of memory used to execute a query, and the relative amount of CPU devoted to processing
a query. Greenplum Database provides two schemes to manage resources - Resource Queues and
Resource Groups.
- Resource groups are an experimental feature and are not intended for use
- in a production environment. Experimental features are subject to change without notice in
- future releases.
+ Resource groups are an experimental feature and are not intended for use in
+ a production environment. Experimental features are subject to change without notice in future
+ releases.Significant Pivotal Greenplum Database performance
+ degradation has been observed when enabling resource group-based workload management on supported versions of RedHat 6.x, CentOS 6.x, and SuSE 11
+ systems. The issue is due to a Linux cgroup kernel bug. The kernel bug has been fixed on
+ CentOS 7.x and Red Hat 7.x systems.
Either the resource queue or the resource group management scheme can be active in Greenplum
Database; both schemes cannot be active at the same time.
Resource queues are enabled by default when you install your Greenplum Database cluster.
While you can create and assign resource groups when resource queues are active, you must
explicitly enable resource groups to start using that management scheme.
- The following table summarizes some of the differences between Resource Queues and Resource Groups.
-
-
-
-
-
-
-
- Metric
- Resource Queues
- Resource Groups
-
-
-
-
- Concurrency
- Managed at the query level
- Managed at the transaction level
-
-
- CPU
- Specify query priority
- Specify percentage of CPU resources; uses Linux Control Groups
-
-
- Memory
- Managed at the queue and operator level; users can over-subscribe
- Managed at the transaction level, with enhanced allocation and tracking; users cannot over-subscribe
-
-
- Memory Isolation
- None
- Memory is isolated between resource groups and between transactions within the same resource group
-
-
- Users
- Limits are applied only to non-admin users
- Limits are applied to SUPERUSER and non-admin users alike
-
-
- Queueing
- Queue only when no slot available
- Queue when no slot is available or not enough available memory
-
-
- Query Failure
- Query may fail immediately if not enough memory
- Query may fail after reaching transaction memory limit
-
-
- Limit Bypass
- Limits are not enforced for SUPERUSER roles and certain operators and functions
- No limit bypass cases
-
-
-
-
-