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added dom obj counting to decide sequential/parallel layout (#10110)

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avadacatavra authored and notriddle committed Jun 8, 2016
1 parent 6c3e948 commit 479a2c12177bd7b031705b5ca66ab8b246059cd9
@@ -175,6 +175,9 @@ pub struct LayoutThread {
/// The workers that we use for parallel operation.
parallel_traversal: Option<rayon::ThreadPool>,

/// Flag to indicate whether to use parallel operations
parallel_flag: bool,

/// Starts at zero, and increased by one every time a layout completes.
/// This can be used to easily check for invalid stale data.
generation: u32,
@@ -389,13 +392,11 @@ impl LayoutThread {
let device = Device::new(
MediaType::Screen,
opts::get().initial_window_size.to_f32() * ScaleFactor::new(1.0));
let parallel_traversal = if layout_threads != 1 {
let configuration =
rayon::Configuration::new().set_num_threads(layout_threads);
rayon::ThreadPool::new(configuration).ok()
} else {
None
};

let configuration =
rayon::Configuration::new().set_num_threads(layout_threads);
let parallel_traversal = rayon::ThreadPool::new(configuration).ok();
debug!("Possible layout Threads: {}", layout_threads);

// Create the channel on which new animations can be sent.
let (new_animations_sender, new_animations_receiver) = channel();
@@ -441,6 +442,7 @@ impl LayoutThread {
font_cache_receiver: font_cache_receiver,
font_cache_sender: ipc_font_cache_sender,
parallel_traversal: parallel_traversal,
parallel_flag: true,
generation: 0,
new_animations_sender: new_animations_sender,
new_animations_receiver: new_animations_receiver,
@@ -978,6 +980,13 @@ impl LayoutThread {
(data.reflow_info.goal == ReflowGoal::ForScriptQuery &&
data.query_type != ReflowQueryType::NoQuery));

// Parallelize if there's more than 750 objects based on rzambre's suggestion
// https://github.com/servo/servo/issues/10110
self.parallel_flag = self.layout_threads > 1 && data.dom_count > 750;
debug!("layout: received layout request for: {}", self.url);
debug!("Number of objects in DOM: {}", data.dom_count);
debug!("layout: parallel? {}", self.parallel_flag);

let mut rw_data = possibly_locked_rw_data.lock();

let element: ServoLayoutElement = match document.root_node() {
@@ -1136,18 +1145,16 @@ impl LayoutThread {
self.time_profiler_chan.clone(),
|| {
// Perform CSS selector matching and flow construction.
match self.parallel_traversal {
None => {
sequential::traverse_dom::<ServoLayoutNode, RecalcStyleAndConstructFlows>(
element.as_node(), &shared_layout_context);
}
Some(ref mut traversal) => {
parallel::traverse_dom::<ServoLayoutNode, RecalcStyleAndConstructFlows>(
element.as_node(), dom_depth, &shared_layout_context, traversal);
}
if let (true, Some(traversal)) = (self.parallel_flag, self.parallel_traversal.as_mut()) {
// Parallel mode
parallel::traverse_dom::<ServoLayoutNode, RecalcStyleAndConstructFlows>(
element.as_node(), dom_depth, &shared_layout_context, traversal);
} else {
// Sequential mode
sequential::traverse_dom::<ServoLayoutNode, RecalcStyleAndConstructFlows>(
element.as_node(), &shared_layout_context);
}
});

// TODO(pcwalton): Measure energy usage of text shaping, perhaps?
let text_shaping_time =
(font::get_and_reset_text_shaping_performance_counter() as u64) /
@@ -1394,19 +1401,17 @@ impl LayoutThread {
self.time_profiler_chan.clone(),
|| {
let profiler_metadata = self.profiler_metadata();
match self.parallel_traversal {
None => {
// Sequential mode.
LayoutThread::solve_constraints(FlowRef::deref_mut(&mut root_flow), &layout_context)
}
Some(ref mut parallel) => {
// Parallel mode.
LayoutThread::solve_constraints_parallel(parallel,
FlowRef::deref_mut(&mut root_flow),
profiler_metadata,
self.time_profiler_chan.clone(),
&*layout_context);
}

if let (true, Some(traversal)) = (self.parallel_flag, self.parallel_traversal.as_mut()) {
// Parallel mode.
LayoutThread::solve_constraints_parallel(traversal,
FlowRef::deref_mut(&mut root_flow),
profiler_metadata,
self.time_profiler_chan.clone(),
&*layout_context);
} else {
//Sequential mode
LayoutThread::solve_constraints(FlowRef::deref_mut(&mut root_flow), &layout_context)
}
});
}
@@ -283,6 +283,12 @@ pub struct Document {
last_click_info: DOMRefCell<Option<(Instant, Point2D<f32>)>>,
/// https://html.spec.whatwg.org/multipage/#ignore-destructive-writes-counter
ignore_destructive_writes_counter: Cell<u32>,
/// Track the total number of elements in this DOM's tree.
/// This is sent to the layout thread every time a reflow is done;
/// layout uses this to determine if the gains from parallel layout will be worth the overhead.
///
/// See also: https://github.com/servo/servo/issues/10110
dom_count: Cell<u32>,
}

#[derive(JSTraceable, HeapSizeOf)]
@@ -454,6 +460,22 @@ impl Document {
self.base_element.set(base.r());
}

pub fn dom_count(&self) -> u32 {
self.dom_count.get()
}

/// This is called by `bind_to_tree` when a node is added to the DOM.
/// The internal count is used by layout to determine whether to be sequential or parallel.
/// (it's sequential for small DOMs)
pub fn increment_dom_count(&self) {
self.dom_count.set(self.dom_count.get() + 1);
}

/// This is called by `unbind_from_tree` when a node is removed from the DOM.
pub fn decrement_dom_count(&self) {
self.dom_count.set(self.dom_count.get() - 1);
}

pub fn quirks_mode(&self) -> QuirksMode {
self.quirks_mode.get()
}
@@ -1880,6 +1902,7 @@ impl Document {
target_element: MutNullableHeap::new(None),
last_click_info: DOMRefCell::new(None),
ignore_destructive_writes_counter: Default::default(),
dom_count: Cell::new(1),
}
}

@@ -2151,10 +2151,12 @@ impl VirtualMethods for Element {
return;
}

let doc = document_from_node(self);
if let Some(ref value) = *self.id_attribute.borrow() {
let doc = document_from_node(self);
doc.register_named_element(self, value.clone());
}
// This is used for layout optimization.
doc.increment_dom_count();
}

fn unbind_from_tree(&self, context: &UnbindContext) {
@@ -2164,10 +2166,12 @@ impl VirtualMethods for Element {
return;
}

let doc = document_from_node(self);
if let Some(ref value) = *self.id_attribute.borrow() {
let doc = document_from_node(self);
doc.unregister_named_element(self, value.clone());
}
// This is used for layout optimization.
doc.decrement_dom_count();
}

fn children_changed(&self, mutation: &ChildrenMutation) {
@@ -1083,6 +1083,7 @@ impl Window {
window_size: window_size,
script_join_chan: join_chan,
query_type: query_type,
dom_count: self.Document().dom_count(),
};

self.layout_chan.send(Msg::Reflow(reflow)).unwrap();
@@ -125,6 +125,8 @@ pub struct ScriptReflow {
pub script_join_chan: Sender<()>,
/// The type of query if any to perform during this reflow.
pub query_type: ReflowQueryType,
/// The number of objects in the dom #10110
pub dom_count: u32,
}

impl Drop for ScriptReflow {

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