1379286 - Use a kernel driver for profiling on Windows

Status: RESOLVED WONTFIX

(Core :: Gecko Profiler, enhancement, P2)

Description

[Jeff Muizelaar [:jrmuizel]]

It should be possible for us to get better profiling results on Windows using a kernel driver for the following reasons:
1. We can have a single piece of code profiling multiple processes instead of one profiler thread per process.
2. Profiling should be lower overhead because we don't need to switch threads
3. We can profile at a higher frequency than 1ms (probably using a performance counter interrupt on the 'UnHalted Core Cycles' or 'UnHalted Reference Cycles' counters)
4. We can get kernel stacks
5. We can performance counter information.

Here are some resources and notes that will be helpful for implementing such a tool:

https://github.com/ipkn/wdd (prototype of an rr tool for windows (has a driver that interacts with the )
https://github.com/GPUOpen-Tools/CxlCommon/blob/master/Src/WinDriverStackWalker/ (the kernel space stack walker used by CodeXL)
https://github.com/jrmuizel/KStack (a simple kernel space stack walker)
https://github.com/opcm/pcm

Some notes on trying to use performance counters:
http://hypervsir.blogspot.ca/2014/11/anybody-knows-how-to-legitimately.html

Comment 1

[Markus Stange [:mstange]]

This might not be needed anymore because we can use the ETW converter for 8000Hz sampling.

Comment 2

[Mayank Bansal]

Is this effectively Fixed by Samply?

Comment 3

[Jeff Muizelaar [:jrmuizel]]

Sure

Comment 4

[Markus Stange [:mstange]]

Let's call it wontfix then - we no longer have a need for using a kernel driver in the Gecko profiler. (Though we could consider having an ETW mode built into the Gecko profiler.)