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<th>Bug ID</th>
<td><a class="bz_bug_link
bz_status_NEW "
title="NEW - Windows system timer resolution needlessly cranked up when nextFireTime is in the past"
href="https://bugs.webkit.org/show_bug.cgi?id=153042">153042</a>
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<th>Summary</th>
<td>Windows system timer resolution needlessly cranked up when nextFireTime is in the past
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<th>Classification</th>
<td>Unclassified
</td>
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<th>Product</th>
<td>WebKit
</td>
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<th>Version</th>
<td>WebKit Nightly Build
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<th>Hardware</th>
<td>PC
</td>
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<th>OS</th>
<td>Windows 7
</td>
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<th>Status</th>
<td>NEW
</td>
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<th>Severity</th>
<td>Normal
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<th>Priority</th>
<td>P2
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<th>Component</th>
<td>Platform
</td>
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<th>Assignee</th>
<td>webkit-unassigned@lists.webkit.org
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<th>Reporter</th>
<td>jnlehner@yahoo.com
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<pre>In <a href="http://trac.webkit.org/browser/trunk/Source/WebCore/platform/win/MainThreadSharedTimerWin.cpp">http://trac.webkit.org/browser/trunk/Source/WebCore/platform/win/MainThreadSharedTimerWin.cpp</a>
if MainThreadSharedTimer::setFireInterval() is called with an interval of 0, as will happen when ThreadTimers::updateSharedTimer() executes
m_sharedTimer->setFireInterval(std::max(nextFireTime - currentMonotonicTime, 0.0));
with nextFireTime in the past, then the following executes:
138 if (Settings::shouldUseHighResolutionTimers()) {
139 if (interval < highResolutionThresholdMsec) {
140 if (!highResTimerActive) {
141 highResTimerActive = true;
142 timeBeginPeriod(timerResolution);
143 }
highResolutionThresholdMsec is 16, so 0 < 16 and we call timeBeginPeriod(1) which stays in effect ~1/3 of a second. This increases power consumption needlessly.
We should only increase the system timer resolution if we're going to actually proceed to the CreateTimerQueueTimer() call; if we're going to PostMessage() immediately no resolution increase is necessary.</pre>
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