Edit Question - KnowledgeHub

Title Body

Background: I have a Java application which does intensive IO on quite large memory mapped files (> 500 MB). The program reads data, writes data, and sometimes does both. All read/write functions have similar computation complexity. I benchmarked the IO layer of the program and noticed strange performance characteristics of memory mapped files: It performs 90k reads per second (read 1KB every iteration at random position) It performs 38k writes per second (write 1KB every iteration sequentially) It performs 43k writes per second (write 4 bytes every iteration at random position) It performs only 9k read/write combined operation per second (read 12 bytes then write 1KB every iteration, at random position) The programs on 64-bit JDK 1.7, Linux 3.4. The machine is an ordinary Intel PC with 8 threads CPU and 4GB physical memory. Only 1 GB was assigned to JVM heap when conducting the benchmark. If more details are needed, here is the benchmark code: https://github.com/HouzuoGuo/Aurinko2/blob/master/src/test/scala/storage/Benchmark.scala And here is the implementation of the above read, write, read/write functions: https://github.com/HouzuoGuo/Aurinko2/blob/master/src/main/scala/aurinko2/storage/Collection.scala So my questions are: Given fixed file size and memory size, what factors affect memory mapped file random read performance? Given fixed file size and memory size, what factors affect memory mapped file random write performance? How do I explain the benchmark result of read/write combined operation? (I was e

Tags (comma-separated) Cancel