Mercurial > hg > graal-compiler
view ASSEMBLY_EXCEPTION @ 1973:631f79e71e90
6974966: G1: unnecessary direct-to-old allocations
Summary: This change revamps the slow allocation path of G1. Improvements include the following: a) Allocations directly to old regions are now totally banned. G1 now only allows allocations out of young regions (with the only exception being humongous regions). b) The thread that allocates a new region (which is now guaranteed to be young) does not dirty all its cards. Each thread that successfully allocates out of a young region is now responsible for dirtying the cards that corresponding to the "block" that just got allocated. c) allocate_new_tlab() and mem_allocate() are now implemented differently and TLAB allocations are only done by allocate_new_tlab(). d) If a thread schedules an evacuation pause in order to satisfy an allocation request, it will perform the allocation at the end of the safepoint so that the thread that initiated the GC also gets "first pick" of any space made available by the GC. e) If a thread is unable to allocate a humongous object it will schedule an evacuation pause in case it reclaims enough regions so that the humongous allocation can be satisfied aftewards. f) The G1 policy is more careful to set the young list target length to be the survivor number +1. g) Lots of code tidy up, removal, refactoring to make future changes easier.
Reviewed-by: johnc, ysr
author | tonyp |
---|---|
date | Tue, 24 Aug 2010 17:24:33 -0400 |
parents | c18cbe5936b8 |
children |
line wrap: on
line source
OPENJDK ASSEMBLY EXCEPTION The OpenJDK source code made available by Oracle at openjdk.java.net and openjdk.dev.java.net ("OpenJDK Code") is distributed under the terms of the GNU General Public License <http://www.gnu.org/copyleft/gpl.html> version 2 only ("GPL2"), with the following clarification and special exception. Linking this OpenJDK Code statically or dynamically with other code is making a combined work based on this library. Thus, the terms and conditions of GPL2 cover the whole combination. As a special exception, Oracle gives you permission to link this OpenJDK Code with certain code licensed by Oracle as indicated at http://openjdk.java.net/legal/exception-modules-2007-05-08.html ("Designated Exception Modules") to produce an executable, regardless of the license terms of the Designated Exception Modules, and to copy and distribute the resulting executable under GPL2, provided that the Designated Exception Modules continue to be governed by the licenses under which they were offered by Oracle. As such, it allows licensees and sublicensees of Oracle's GPL2 OpenJDK Code to build an executable that includes those portions of necessary code that Oracle could not provide under GPL2 (or that Oracle has provided under GPL2 with the Classpath exception). If you modify or add to the OpenJDK code, that new GPL2 code may still be combined with Designated Exception Modules if the new code is made subject to this exception by its copyright holder.