[webkit-dev] JS binding wapper pointers: inline vs. separate hash table
mjs at apple.com
Wed Oct 1 10:54:21 PDT 2008
On Oct 1, 2008, at 10:50 AM, Geoffrey Garen wrote:
>>> If we believe that JS wrappers are relatively uncommon, we can
>>> store them in a Node's "rare data" structure, and bloat only those
>>> uncommon nodes that have JS wrappers.
>> Depending on exactly how common they are, this could be more net
>> memory use, if it causes Nodes to have a NodeRareData structure
>> that wouldn't otherwise.
>>> If we believe that JS wrappers are relatively common, we can store
>>> them directly in a Node, since putting them in a hashtable is net
>>> more memory use.
>> I think only a minority of nodes have wrappers, but on at least
>> some pages it is likely to be a sizable minority. I did not measure
>> though - should have.
> I should also mention Sam's suggestion, which I think is pretty
> good: All HTMLElements (or perhaps all Elements) get embedded
> is relatively common. All other DOM objects, including generic
> nodes, use a hash table.
That would probably cut the memory use significantly. On the other
hand I bet there are some large pages where few of the nodes ever get
a JS wrapper in the lifetime of the page (such as cnn.com, slashdot,
or the Wikipedia page I cited).
To make the right tradeoff we'll also need an estimate of the speed
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