Author: Inaam Rana <firstname.lastname@example.org>
Date: Thu Mar 6 09:51:27 2014 -0500
Buffer pool list scan optimization
Feature: Optimize Buffer Pool List Scans and Fix Reporting
This patch includes:
– backport of upstream work around buffer pool list scan.
committer: Sunny Bains <Sunny.Bains@Oracle.Com>
branch nick: trunk
timestamp: Fri 2013-08-09 08:37:45 +1000
WL#7047 - Optimize buffer pool list scans and related batch processin
Reduce excessive scanning of pages when doing flush list batches. The
fix is to introduce the concept of "Hazard Pointer", this reduces the
time complexity of the scan from O(n*n) to O.
The concept of hazard pointer is reversed in this work. Academically
hazard pointer is a pointer that the thread working on it will declar
such and as long as that thread is not done no other thread is allowe
do anything with it.
In this WL we declare the pointer as a hazard pointer and then if any
thread attempts to work on it, it is allowed to do so but it has to a
the hazard pointer to the next valid value. We use hazard pointer sol
reverse traversal of lists within a buffer pool instance.
Add an event to control the background flush thread. The background f
thread wait has been converted to an os event timed wait so that it c
signalled by threads that want to kick start a background flush when
buffer pool is running low on free/dirty pages.