From 888fbacfe0b1c71e2d7cbd1552aca6f424dc0d93 Mon Sep 17 00:00:00 2001 From: Andrew McCreight Date: Tue, 29 Jan 2019 13:36:19 +0100 Subject: Increase slice time for longer running CCs. If a CC takes too long (around 50 slices) or gets interrupted by a GC, we have to finish it synchronously, which can cause a big pause. This patch tries to avoid that by eagerly increasing the slice budget the longer a CC goes on. It linearly increases the slice time from 5ms to 40ms as we approach the halfway point of a CC (1 second), matching GC pauses, and then leaves it at 40ms. --- dom/base/nsJSEnvironment.cpp | 17 ++++++++++++++--- 1 file changed, 14 insertions(+), 3 deletions(-) (limited to 'dom') diff --git a/dom/base/nsJSEnvironment.cpp b/dom/base/nsJSEnvironment.cpp index ebce7ea3f..3f28533d3 100644 --- a/dom/base/nsJSEnvironment.cpp +++ b/dom/base/nsJSEnvironment.cpp @@ -1355,9 +1355,20 @@ nsJSContext::RunCycleCollectorSlice() TimeStamp now = TimeStamp::Now(); // Only run a limited slice if we're within the max running time. - if (TimeBetween(gCCStats.mBeginTime, now) < kMaxICCDuration) { - float sliceMultiplier = std::max(TimeBetween(gCCStats.mEndSliceTime, now) / (float)kICCIntersliceDelay, 1.0f); - budget = js::SliceBudget(js::TimeBudget(kICCSliceBudget * sliceMultiplier)); + uint32_t runningTime = TimeBetween(gCCStats.mBeginTime, now); + if (runningTime < kMaxICCDuration) { + // Try to make up for a delay in running this slice. + float sliceDelayMultiplier = TimeBetween(gCCStats.mEndSliceTime, now) / (float)kICCIntersliceDelay; + float delaySliceBudget = kICCSliceBudget * sliceDelayMultiplier; + + // Increase slice budgets up to |maxLaterSlice| as we approach + // half way through the ICC, to avoid large sync CCs. + float percentToHalfDone = std::min(2.0f * runningTime / kMaxICCDuration, 1.0f); + const float maxLaterSlice = 40.0f; + float laterSliceBudget = maxLaterSlice * percentToHalfDone; + + budget = js::SliceBudget(js::TimeBudget(std::max({delaySliceBudget, + laterSliceBudget, (float)kICCSliceBudget}))); } } } -- cgit v1.2.3