runtime: Profiling API Documentation: ELT APIs (SetEnterLeaveFunctionHooks*, etc.) do not work on MacOSX
I couldn’t find any evidence of the stubs that are required for ELT to function properly in Linux and/or MacOSX x64
It’s best if we document that this can/will fail the target process spectacularly, i.e. the profiler author must not pass COR_PRF_MONITOR_ENTERLEAVE to SetEventMask. Particularly because SetEventMask may succeed (I vaguely remember it did in fact succeed in my testing) and that the program from then on may be exhibiting undefined behavior.
I’ll open a separate issue to track the fact this work needs to happen for our currently supported platforms.
About this issue
- Original URL
- State: closed
- Created 8 years ago
- Comments: 22 (17 by maintainers)
Yes @noahfalk you are right. But it’s ok, I figured it out using the ELT hooks.
The challenge is that I maintain a profiler that has been based on Windows only for a long time. There were plenty of examples to go off of for that, and MASM integrated with VS/MSBUILD was the way to go.
In the examples given to me prior on different issues in this repo (“look at asmhelpers.S”), there is a huge gap: I don’t know the coreclr repo / build process well. The example made sense on paper, but I’ve been used to using MASM on Windows, and took me a lot of trial, error, and digging to realize that the file suggested for reference was using intel syntax with GCC (rather than NASM or GAS; not to mention this sample profiler above referenced uses clang). But, I now have it working.
All that to say; for those of us that have built tooling around the APIs provided in the original, full framework, the tools were at least familiar and we could make it work. In this new world, some of us are having to learn a lot of new things - and I think this entire repo could use a lot more “how to” for people like myself (I can pull it and build it… and use the output). But the build process / tool chain / test projects, etc are a steep learning curve. I’ve learned a lot more from 3rd parties / bloggers than I have from the project itself. I think you’d have a lot more people contributing if they understood these things better - .net developers are fairly stuck in a certain ecosystem, and getting them to contribute to something where they have little to no knowledge of the tooling, etc, is difficult.
Internal testing revealed an issue with ReJIT on MacOS, but apart from that, the ELT APIs are fully functional and have been tested on macOS. The change that enabled this is dotnet/coreclr#12603, which enabled it for AMD64/Linux, but macOS is thankfully only on x64 architecture so this enabled the ELT callbacks on macOS as well.
I will follow up with a PR to update the Profiler API documentation on this repo to update this recent progress.
[EDIT] ReJIT issue is actually an issue with our testing infra.
Will be marking this issue as solved, since ELT callbacks are fully functional.
I am in progress of testing the profiler APIs on macOS. Here is a list of the tests in the process of being brought up: (checked means they’ve been brought up AND are all passing the internal profiler tests)