====== Pmctools: Plan of Work ======

**Current Plan:** Callgraph support

Callgraph support requires changes to the kernel to
capture a stack at the time of the PMC NMI interrupt.
It also requires changes to the userland API
(**libpmc(3)**) and reporting tools (**pmcstat(8)**).

The current approach of using **gprof(1)** for the final
display of profiling data is suboptimal for analysing
callgraphs that span executable modules.
**pmcstat(8)** will need to be enhanced to support
callgraphs directly.  I'm planning to do this in the
following phases:

  - Implement a cross-platform **libelf(3)** API.  One of my goals is to create a cross-platform performance analysis toolset.  Rather than parsing ELF files directly in **pmcstat**, as most of our other tools do (e.g., **gprof**, **readelf**, others), I'd rather use a **libelf** API for **pmcstat** //and// the other tools.  See wiki page "[[/LibElf|LibElf]]".  //Status: Completed, and in -current/%%FreeBSD%% 7.//
  - Implement cross-module callgraph support in **pmcstat**.  The hwpmc log will contain call graph information that could traverse module boundaries (e.g., calls from an executable into a shared library).  //Status: completed in Perforce, undergoing community review.//
  - Implement code to capture callgraphs inside the **hwpmc(4)** driver.  //Status: completed in Perforce, and undergoing community review.//

A patch against recent -CURRENT (Aug 2007) may be found at:
[[http://people.freebsd.org/~jkoshy/download/pmctools-callgraph-patch.gz|http://people.freebsd.org/~jkoshy/download/pmctools-callgraph-patch.gz]].

**Near Future**

Stuff that needs to be done in the near future:

  * Implement a proper test suite for **hwpmc(4)** and **libpmc(3)**.  Since **hwpmc(4)** can log data remotely, I looked around for a test framework that can manage distributed test cases.  I found TET 3.7, which I'm happy with.  See also: [[/TetIntegration|TetIntegration]].
  * Bugs reported in [[PmcTools/KnownBugs|PmcTools/KnownBugs]] need to be fixed.

For longer term work, please see [[PmcTools/PmcResearch|PmcTools/PmcResearch]].