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Slightly optimize Workspace::xStackingOrder 

Callgrind analysis showed that this method has room for improvement.
The bottle neck is mapping the Unmanaged against the list of windows
retreived from xcb_query_tree. The number of windows in that list is
rather large (>1000), which turns the loop into an expensive path.
Workspace::findUnmanaged seems to be too expensive for that due to the
overhead of using a functor and multiple method calls. The Inl. cost
before the optimization for checking ~55,000 windows is 2.46.

The change uses a good old const-iterator based loop over the unmanaged
list to check for the window. This reduces the Incl. cost for checking
~55,000 windows to 0.28.

REVIEW: 122067
icc-effect-5.14.5
Martin Gräßlin 2015-01-15 08:32:11 +01:00
parent f643b71902
commit f7d7c246b8
1 changed files with 14 additions and 3 deletions
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17
layers.cpp
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@ -670,11 +670,22 @@ ToplevelList Workspace::xStackingOrder() const
x_stacking.append(c);
xcb_window_t *windows = tree.children();
const auto count = tree->children_len;
int foundUnmanagedCount = unmanaged.count();
for (unsigned int i = 0;
i < tree->children_len;
i < count;
++i) {
if (Unmanaged* c = findUnmanaged(windows[i]))
x_stacking.append(c);
for (auto it = unmanaged.constBegin(); it != unmanaged.constEnd(); ++it) {
Unmanaged *u = *it;
if (u->window() == windows[i]) {
x_stacking.append(u);
foundUnmanagedCount--;
break;
}
}
if (foundUnmanagedCount == 0) {
break;
}
}
if (m_compositor) {
const_cast< Workspace* >(this)->m_compositor->checkUnredirect();