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mechanical-sympathy.blogspot.com

Mechanical Sympathy: Simple Binary Encoding

http://mechanical-sympathy.blogspot.com/2014/05/simple-binary-encoding.html

Hardware and software working together in harmony. Monday, 5 May 2014. Financial systems communicate by sending and receiving vast numbers of messages in many different formats. When people use terms like "vast" I normally think, "really.how many? So lets quantify "vast" for the finance industry. Market data feeds from financial exchanges typically can be emitting tens or hundreds of thousands of message per second, and aggregate feeds like OPRA. Last year the CME, who are a member the FIX community.

mechanical-sympathy.blogspot.com

Mechanical Sympathy: August 2013

http://mechanical-sympathy.blogspot.com/2013_08_01_archive.html

Hardware and software working together in harmony. Monday, 26 August 2013. Lock-Based vs Lock-Free Concurrent Algorithms. Last week I attended a review session of the new JSR166. Run by Heinz Kabutz. At the excellent JCrete. Unconference. StampedLock is an attempt to address the contention issues that arise in a system when multiple readers concurrently access shared state. StampedLock is designed to perform better than ReentrantReadWriteLock. By taking an optimistic read approach. Each implementation is...

mechanical-sympathy.blogspot.com

Mechanical Sympathy: Memory Access Patterns Are Important

http://mechanical-sympathy.blogspot.com/2012/08/memory-access-patterns-are-important.html

Hardware and software working together in harmony. Sunday, 5 August 2012. Memory Access Patterns Are Important. The 1994 paper " Hitting the memory wall: implications of the obvious. Describes the problem and goes on to argue that caches do not ultimately help because of compulsory cache-misses. I aim to show that by using access patterns which display consideration for the cache hierarchy, this conclusion is not inevitable. Memory accessed recently will likely be required again soon. Pseudo randomly wal...

mechanical-sympathy.blogspot.com

Mechanical Sympathy: Java Garbage Collection Distilled

http://mechanical-sympathy.blogspot.com/2013/07/java-garbage-collection-distilled.html

Hardware and software working together in harmony. Tuesday, 16 July 2013. Java Garbage Collection Distilled. Serial, Parallel, Concurrent, CMS, G1, Young Gen, New Gen, Old Gen, Perm Gen, Eden, Tenured, Survivor Spaces, Safepoints, and the hundreds of JVM startup flags. Does this all baffle you when trying to tune the garbage collector while trying to get the required throughput and latency from your Java application? Wise folk keep telling us, “You do not get something for nothing”. The time taken by sys...

mechanical-sympathy.blogspot.com

Mechanical Sympathy: December 2012

http://mechanical-sympathy.blogspot.com/2012_12_01_archive.html

Hardware and software working together in harmony. Wednesday, 19 December 2012. Mechanical Sympathy Discussion Group. Lately a number of people have suggested I start a discussion group on the subject of mechanical sympathy, so I've taken the plunge and done it! The group can be a place to discuss topics related to writing software which works in harmony with the underlying hardware to gain great performance. Https:/ groups.google.com/forum/? Posted by Martin Thompson. Location: London, UK. In my last po...

mechanical-sympathy.blogspot.com

Mechanical Sympathy: Printing Generated Assembly Code From The Hotspot JIT Compiler

http://mechanical-sympathy.blogspot.com/2013/06/printing-generated-assembly-code-from.html

Hardware and software working together in harmony. Thursday, 27 June 2013. Printing Generated Assembly Code From The Hotspot JIT Compiler. This blog illustrates how to install a Disassembler Plugin. And provides command line options for targeting a particular method. Previously it was necessary to obtain a debug build for printing the assembly code generated by the Hotspot JIT for the Oracle/SUN JVM. Since Java 7, it has been possible to print the generated assembly code if a Disassembler Plugin. It is p...

mechanical-sympathy.blogspot.com

Mechanical Sympathy: False Sharing

http://mechanical-sympathy.blogspot.com/2011/07/false-sharing.html

Hardware and software working together in harmony. Saturday, 30 July 2011. Doubles (8) and longs (8). Ints (4) and floats (4). Shorts (2) and chars (2). Booleans (1) and bytes (1). Repeat for sub-class fields. With this knowledge we can pad a cache line between any fields with 7 longs. Within the Disruptor. We pad cache lines around the RingBuffer. To show the performance impact let’s take a few threads each updating their own independent counters. These counters will be volatile long. Will be laid out i...

mechanical-sympathy.blogspot.com

Mechanical Sympathy: June 2013

http://mechanical-sympathy.blogspot.com/2013_06_01_archive.html

Hardware and software working together in harmony. Thursday, 27 June 2013. Printing Generated Assembly Code From The Hotspot JIT Compiler. This blog illustrates how to install a Disassembler Plugin. And provides command line options for targeting a particular method. Previously it was necessary to obtain a debug build for printing the assembly code generated by the Hotspot JIT for the Oracle/SUN JVM. Since Java 7, it has been possible to print the generated assembly code if a Disassembler Plugin. It is p...