1 / 14

Operating System Support for Performance Monitoring

Operating System Support for Performance Monitoring. Witawas Srisa-an Chapter: not in the book. Imagine …. Tom is deploying a new server program for his client. During the field test, he notices that its performance is below his expectation. How would he identify the main causes?

sagira
Download Presentation

Operating System Support for Performance Monitoring

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Operating System Support for Performance Monitoring Witawas Srisa-an Chapter: not in the book Operating System Kernels

  2. Imagine … • Tom is deploying a new server program for his client. During the field test, he notices that its performance is below his expectation. How would he identify the main causes? • A company is planning to upgrade the server systems. You are asked to analyze which systems and which configurations will perform best when executing its main point-of-sale application. How would you perform the analysis? Operating System Kernels

  3. Imagine … • You are deploying an embedded computer system that will run only 3 applications simultaneously. You are asked to hand tuned these three applications to minimize: • Instruction count • Execution time in cycles • L1 data cache misses • Pipeline stalls, etc. • You want to compare the performance of your very own malloc function to existing techniques. How would you conduct the comparison? Operating System Kernels

  4. Remember? Operating System Kernels

  5. Outline • What are Model Specific Registers (MSRs) • Why are they there? • How do we use them in the OS context? Operating System Kernels

  6. MSRs • Programmable registers to satisfy performance cognizant consumers • A small number (2 in P1, 4 in Athlon, 8 in P4) • Can count several on-going events • Each counter has a control register • Set interrupts on overflow • Cycle detection versus event detection • Work in various privilege levels • Set the event(s) to monitor Operating System Kernels

  7. MSRs • Currently supported by many architectures • AMD Athlon, Opteron • HP (DEC or Compaq) Alpha • Intel Itanium, Pentium • Sun UltraSparc II • Many more Operating System Kernels

  8. MSRs • Intel • P1: RDTSC and 2 MSRs • P4: RDTSC and 9 registers to monitor 48 events • AMD • Athlon & Opteron: RDTSC and 4 registers to monitor 58+ events Operating System Kernels

  9. MSRs • L1 Misses • Load-Store Buffer Full • Dispatched Floating Point Unit operations • Cycle counter • many many more events Operating System Kernels

  10. MSRs • RDTSC (in X86) • A special 64 bit register • Stored the cycle counter value in eax and ecx • Start from zero when the machine is booted • For a 3GHz, takes about 195 years to roll over Operating System Kernels

  11. MSRs • Not well documented • No APIs support • Change frequently • Last thing on the (long) to-do list of the hardware engineers Sounds great! What’s the catch? Operating System Kernels

  12. No More Wall Clock Time? • Yes, cycle counting is more accurate • Yes, monitoring micro-architecture events give us more insights • No, the information is still system wide. • Getting L1 misses in a system with 105 processes. What does that tell you about each process? Operating System Kernels

  13. Performance Monitoring in the OS Context • The focus of Programming Assignment 2 • To obtain events information per process • Simplified by using RDTSC • Create new system calls to provide per process information What do we need from the OS? Operating System Kernels

  14. OS support new ready running exit blocked Operating System Kernels

More Related