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This CL fixes a long standing issue where reentering TimedHistograms scopes would cause spurious measurements. Only the non-nested scopes yielded correct results. Due to the changed numbers, the V8.Execute histogram is renamed to V8.ExecuteMicroSeconds. Note that this histogram is also guarded behind the --slow-histograms flag due to the additional overhead. Unlike before, it does no longer include time for external callbacks and only measures self time. The following example illustrates the new behaviour: 1. Enter V8: |--+.......+--| self-time: 4 units (reported) 2. Exit V8 (callback): |-+...+-| self-time: 2 units (ignored) 3. Re-enter V8: |---| self-time: 3 units (reported) This would result in 2 histogram entries with 4 time units for the first V8 slice and 3 units for the nested part. Note that the callback time itself is ignored. This CL attempts to clean up how TimedHistograms work: - Histogram: the base class - TimedHistograms: used for time-related histograms that are not nested - NestedTimeHistograms: Extends TimedHistograms and is used for nested histograms This CL changes Histograms to not measure time themselves. Measurements happen in the *HistogramScopes: - BaseTimedHistogramScope: Base functionality - TimedHistogramScope: For non-nested measurements - NestedTimedHistogramScope: For nested measurements - PauseNestedTimedHistogramScope: Ignore time during a given scope. This is used to pause timers during callbacks. Additional changes: - ExternalCallbackScope now contains a PauseNestedTimedHistogramScope and always sets VMState<EXTERNAL> Bug: v8:11946 Change-Id: I45e4b7ff77b5948b605dd50539044cb26222fa21 Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3001345 Reviewed-by: Omer Katz <omerkatz@chromium.org> Reviewed-by: Thibaud Michaud <thibaudm@chromium.org> Reviewed-by: Victor Gomes <victorgomes@chromium.org> Reviewed-by: Leszek Swirski <leszeks@chromium.org> Commit-Queue: Camillo Bruni <cbruni@chromium.org> Cr-Commit-Position: refs/heads/master@{#76111} |
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| .. | ||
| condition-variable-unittest.cc | ||
| mutex-unittest.cc | ||
| platform-unittest.cc | ||
| semaphore-unittest.cc | ||
| time-unittest.cc | ||