[GitHub] [systemds] philipportner commented on a change in pull request #1147: Unified Memory Manager design proposal

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philipportner commented on a change in pull request #1147:
URL: https://github.com/apache/systemds/pull/1147#discussion_r559781921



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File path: scripts/staging/unified-memory-manager/umm.md
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+<!--
+{% comment %}
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements.  See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to you under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+{% end comment %}
+-->
+
+# Unified Memory Manager - Design Document
+
+| **Author(s)** | Philipp Ortner |
+:-------------- |:----------------------------------------------------|
+
+## Description
+This document describes the initial design of an Unified Memory Manager proposed
+for SystemDS.
+
+## Design
+The Unified Memory Manager, henceforth UMM, will act as a manager for heap memory
+provided by the JVM.
+
+The UMM has a certain (% of JVM heap) amount of memory which it can distribute for operands
+and a buffer pool.
+
+Operands are the compiled programs variables which extends the base class 
+`Data`, e.g., `MatrixObject` and `StringObject`.
+The buffer pool manages
+in memory representation of dirty objects that don't exist on the HDFS or 
+other persistent memory. This is currently done by the `LazyWriteBuffer`. Intermediates
+could be represented in this buffer.
+
+These two memory areas each will have a min and max amount of memory it can
+occupy, meaning that the boundary for the areas can shift dynamically depending
+on the current load.
+
+||min|max|
+| ------------- |:-------------:| -----:|
+| operations  | 50% | 70% |
+| buffer pool | 15% | 30% |
+
+The UMM will utilise the existing `CacheBlock` structure to manage the buffer
+pool area while it will use the new `OperandBlock (?)` structure to keep track of
+operations.
+
+### UMM Java Class
+For starters, we want to keep the API rather simple.
+
+```java
+/**
+ * Pins the input block into main memory.
+ * The provided block needs to fit into UMM boundaries.
+ */
+void pin(String, Block);
+
+/**
+ * Unpins the input block from main memory.
+ */
+void unpin(String);
+
+/**
+ * Loads the block into memory and pins it, if not evicted just pins it(?)
+ * The requested block needs to fit into UMM boundaries.
+ */
+Block serve(String);
+
+/**
+ * Reserves an specified amount in one of the two memory areas.
+ * The requested block needs to fit into UMM boundaries.
+ */
+Block reserve(Size, MemoryArea);

Review comment:
       Yes, I thought one may want the handle as soon as the memory is reserved.  If that's not the case I'll make it `void reserve(Size)`.

##########
File path: scripts/staging/unified-memory-manager/umm.md
##########
@@ -0,0 +1,144 @@
+<!--
+{% comment %}
+Licensed to the Apache Software Foundation (ASF) under one or more
+contributor license agreements.  See the NOTICE file distributed with
+this work for additional information regarding copyright ownership.
+The ASF licenses this file to you under the Apache License, Version 2.0
+(the "License"); you may not use this file except in compliance with
+the License.  You may obtain a copy of the License at
+
+http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+{% end comment %}
+-->
+
+# Unified Memory Manager - Design Document
+
+| **Author(s)** | Philipp Ortner |
+:-------------- |:----------------------------------------------------|
+
+## Description
+This document describes the initial design of an Unified Memory Manager proposed
+for SystemDS.
+
+## Design
+The Unified Memory Manager, henceforth UMM, will act as a manager for heap memory
+provided by the JVM.
+
+The UMM has a certain (% of JVM heap) amount of memory which it can distribute for operands
+and a buffer pool.
+
+Operands are the compiled programs variables which extends the base class 
+`Data`, e.g., `MatrixObject` and `StringObject`.
+The buffer pool manages
+in memory representation of dirty objects that don't exist on the HDFS or 
+other persistent memory. This is currently done by the `LazyWriteBuffer`. Intermediates
+could be represented in this buffer.
+
+These two memory areas each will have a min and max amount of memory it can
+occupy, meaning that the boundary for the areas can shift dynamically depending
+on the current load.
+
+||min|max|
+| ------------- |:-------------:| -----:|
+| operations  | 50% | 70% |
+| buffer pool | 15% | 30% |
+
+The UMM will utilise the existing `CacheBlock` structure to manage the buffer
+pool area while it will use the new `OperandBlock (?)` structure to keep track of
+operations.
+
+### UMM Java Class
+For starters, we want to keep the API rather simple.
+
+```java
+/**
+ * Pins the input block into main memory.
+ * The provided block needs to fit into UMM boundaries.
+ */
+void pin(String, Block);
+
+/**
+ * Unpins the input block from main memory.
+ */
+void unpin(String);

Review comment:
       Not quite sure how I would merge that with `resize_reserved`.
   `void unpin(String, Size)` and move the block from operation memory to the buffer pool and drop/resize if already in buffer pool?




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