[ignite] branch master updated: IGNITE-10639 Improve doc for page memory (#5702)

[dpavlov]

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The following commit(s) were added to refs/heads/master by this push:
     new bd6bc43  IGNITE-10639 Improve doc for page memory (#5702)
bd6bc43 is described below

commit bd6bc433bc33d500254c799f9c4f502c42b6accd
Author: Dmitriy Pavlov <dpav...@apache.org>
AuthorDate: Thu Jan 3 16:53:55 2019 +0300

    IGNITE-10639 Improve doc for page memory (#5702)
    
     IGNITE-10639 Proof of concept for an internal description for packages
---
 .../pagemem/PagesWriteSpeedBasedThrottle.java      |  4 ++-
 .../processors/cache/persistence/pagemem/README.md | 30 ++++++++++++++++++++--
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git 
a/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/PagesWriteSpeedBasedThrottle.java
 
b/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/PagesWriteSpeedBasedThrottle.java
index 2dd8127..9e4975c 100644
--- 
a/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/PagesWriteSpeedBasedThrottle.java
+++ 
b/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/PagesWriteSpeedBasedThrottle.java
@@ -29,7 +29,9 @@ import org.apache.ignite.internal.util.typedef.internal.U;
 /**
  * Throttles threads that generate dirty pages during ongoing checkpoint.
  * Designed to avoid zero dropdowns that can happen if checkpoint buffer is 
overflowed.
- * Uses average checkpoint write speed and moment speed of marking pages as 
dirty.
+ * Uses average checkpoint write speed and moment speed of marking pages as 
dirty.<br>
+ *
+ * See also: <a 
href="https://github.com/apache/ignite/tree/master/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem#speed-based-throttling";>Speed-based
 throttling description</a>.
  */
 public class PagesWriteSpeedBasedThrottle implements PagesWriteThrottlePolicy {
     /** Maximum dirty pages in region. */
diff --git 
a/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/README.md
 
b/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/README.md
index 57e623d..0244d45 100644
--- 
a/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/README.md
+++ 
b/modules/core/src/main/java/org/apache/ignite/internal/processors/cache/persistence/pagemem/README.md
@@ -2,11 +2,37 @@ Apache Ignite Native Peristence Page Memory
 -------------------------------------------
 This package contains page memory implementation for case persitence is 
enabled.
 
-Speed Based Throttling
-----------------------
+## Loaded Pages Table
+
+An implementation of [LoadedPagesMap.java](LoadedPagesMap.java)
+(PageIdTable) manages mapping from Page ID to relative pointer map (rowAddr).
+
+See introduction in wiki [Region 
Structure](https://cwiki.apache.org/confluence/display/IGNITE/Ignite+Durable+Memory+-+under+the+hood#IgniteDurableMemory-underthehood-Regionandsegmentstructure).
+
+<img 
src="https://cwiki.apache.org/confluence/rest/gliffy/1.0/embeddedDiagrams/e9df3b17-1a57-487c-a842-dbb6b1062709.png";>
+
+Current implementation is 
[RobinHoodBackwardShiftHashMap.java](RobinHoodBackwardShiftHashMap.java)
+
+## Throttling
+Throttling is an intentional slowdown of operation in the grid to equate 
throughput of the storage and speed of user operations.
+
+Throttling is implemented at physical level of operations, so it operates not 
with user entries, but with page memory pages.
+
 For an introduction, please see
 [wiki 
PagesWriteThrottling](https://cwiki.apache.org/confluence/display/IGNITE/Ignite+Persistent+Store+-+under+the+hood#IgnitePersistentStore-underthehood-PagesWriteThrottling)
 
+There are two types of throttling implemented in Apache Ignite:
+* Checkpoint buffer overflow protection.
+
+This CP Buffer throttling is enabled by default. It is activated if CP buffer 
is close to being filled.
+In this case, there is an exponential backoff at 2/3 when filling reached.
+Since the CP buffer is being cleaned as the checkpoint progresses, this more 
or less behaves like trotting.
+
+* the whole region marked dirty protection.
+This type of throttling protects region segments from being completely filled 
by dirty pages when checkpoint progress is far from completion.
+
+### Speed Based Throttling
+
 If throttling is enabled in User configuration, then Speed based throttling is 
applied.
 
 Speed based throttling is implemented by