- 01 Apr, 2021 1 commit
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Sara Tang authored
Feedback from Microsoft partners indicates that it would be beneficial to enable ETW stack-walking events by default. This is difficult, because the --interpreted-frames-native-stack flag comes with a significant perf degradation. Ideally, we would turn this flag on dynamically, only when a ETW recorder is actively triggering the provider. Unfortunately, the flag in its current state cannot be enabled dynamically. In light of this, we have decided to only flip the build flag. Bug: v8:11043 Change-Id: Id883b9bcd635b41139450ab2d5c92511422525a3 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2773792Reviewed-by: Camillo Bruni <cbruni@chromium.org> Commit-Queue: Sara Tang <sartang@microsoft.com> Cr-Commit-Position: refs/heads/master@{#73784}
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- 02 Mar, 2021 1 commit
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Sara Tang authored
Design doc: https://docs.google.com/document/d/1xkXj94iExFgLWc_OszTNyNGi523ARaKMWPZTeomhI4U This is the second (and hopefully final!) change list needed to integrate ETW into V8. In particular, we added stack-walking functionality for JIT-ted functions! Some notes on instrumentation: - The gist of getting stack-walking in ETW is we need to emit events with specific event IDs. These events get stitched into a pseudo-PDB that is recognizable by ETW. - Unfortunately, we cannot rely on the TraceLogging API from the first CL, as it does not support specifying event IDs. Instead, Bill Ticehurst wrote an API that peels back the TraceLogging API just enough so that we can specify event IDs. This API is the entirety of etw-metdata.h - We attach a CodeEventHandler that logs a stack-walking event whenever code movement is triggered. Bug: v8:11043 Change-Id: I1bf57c985b7375f045089027855b1c03878abb78 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2616221Reviewed-by: Camillo Bruni <cbruni@chromium.org> Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Commit-Queue: Sara Tang <sartang@microsoft.com> Cr-Commit-Position: refs/heads/master@{#73145}
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- 05 Jan, 2021 1 commit
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Sara Tang authored
Design doc: https://docs.google.com/document/d/1xkXj94iExFgLWc_OszTNyNGi523ARaKMWPZTeomhI4U A lot has changed since the last patchset! I recommend revisiting this design doc and reading the parts in green. I explain the roadmap for what changes to expect from ETW instrumentation as well as the instrumentation of this particular CL. I'll do my best to answer any further questions anyone has about my particular instrumentation or ETW in general :) --- This is the first of a series of changelists to round out ETW instrumentation for V8. This changelist represents the most minimal change needed to instrument ETW in V8. In particular, it: - defines and registers the ETW provider, - interacts minimally with the rest of V8, by hooking into the existing TracingController::AddTraceEvent function, - is designed with a platform-agnostic layer, so that event tracers for other platforms can be instrumented in teh future. Some notes on instrumentation (aka I copied stuff from the design doc): We make heavy use of the TraceLogging API to log events. It differs from previous methods of emitting ETW events in that it doesn<E2><80><99>t require the overhead of a separate manifest file to keep track of metadata; rather, events using this API are self-descriptive. Here are the five major steps to instrument the TraceLogging API: - Forward declare the provider (from provider-win.h) - Define the provider in a .cc file (from provider-win.cc) - Register the provider (called from v8.cc). - Write events (called from libplatform/tracing-controller.cc) - Unregister the provider (called from v8.cc) At the base, we have an abstract provider class that encapsulates the functionality of an event provider. These are things like registering and unregistering the provider, and the actual event-logging. The provider class is split into provider-win and provider-mac (currently not instantiated) classes, with OS-dependent implementations of the above functions. In particular, the TraceLogging API is used only in provider-win. It is here that we forward declare and define the provider, as well as write ETW events. Finally, there is a v8-provider class that serves as a top-level API and is exposed to the rest of V8. It acts as a wrapper for the platform-specific providers. The .wprp file is needed so that Windows Performance Recorder knows how to capture our events. Some considerations: - Is TracingController::AddTraceEvent the best place from which to write my events? - Is src/libplatform/tracing the best place to put my instrumentation? - Right now, I fail the preupload because of this, which tells me my files are probably not in the best location: You added one or more #includes that violate checkdeps rules. src\init\v8.cc Illegal include: "src/libplatform/tracing/v8-provider.h" Because of "-src/libplatform" from src's include_rules. Change-Id: Id53e4a034c9e526524a17000da0a647a95d93edf Bug: v8:11043 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2233407Reviewed-by: Ulan Degenbaev <ulan@chromium.org> Reviewed-by: Peter Marshall <petermarshall@chromium.org> Commit-Queue: Sara Tang <sartang@microsoft.com> Cr-Commit-Position: refs/heads/master@{#71918}
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