[Webkit-unassigned] [Bug 66904] New: Caching Parsed results (CSSRuleSet) for CSS files

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=66904

           Summary: Caching Parsed results (CSSRuleSet) for CSS files
           Product: WebKit
           Version: 528+ (Nightly build)
          Platform: All
        OS/Version: All
            Status: UNCONFIRMED
          Severity: Normal
          Priority: P3
         Component: CSS
        AssignedTo: webkit-unassigned at lists.webkit.org
        ReportedBy: s.kalasapur at samsung.com
                CC: koivisto at iki.fi


Currently WebKit does not cache the parsed results from included external CSS files. 
The operation of parsing all included CSS files is quite expensive, and for some popular websites (ex: youtube), the cumulative time taken to parse all external CSS files can be upto a few percentage points (ex: for youtube, it incurs around 3 ~ 7 %, many other websites also incur a few % points) of pageload time. 
By keeping the parsed results in cache, and re-using them for future requests (ex: another URL from youtube.com domain), we can reduce the time taken for pageload.

(Patch to follow)

Here is some data for Youtube domain urls:
(Based on GTK build of WebKit nightly r93508 on Ubuntu), numbers averaged over 10 iterations (run on the same day)

Visited URL    CSS URL        
1. http://www.youtube.com/ - PageLoad time: 1952    , Pageload time when caching enabled: 2261
    http://s.ytimg.com/yt/cssbin/www-core-vflT2SXA2.css - ParseTime: 47.87, parse time with caching: 40.915967
            Parse time as % of pageload    2.4523565574, with caching: 1.80

2. http://www.youtube.com/music - PageLoad time:1685    , pageload time with caching: 1278
    http://s.ytimg.com/yt/cssbin/www-core-vflT2SXA2.css - Parsetime: 37.13, with caching: 0.63
    http://s.ytimg.com/yt/cssbin/www-the-rest-vflNb6rAI.css - ParseTime: 3, with caching: 1.12
    http://s.ytimg.com/yt/cssbin/www-browse-new-vfl89j8Ia.css - ParseTime: 17.07, with caching: 6.4
                        Cumulative parsing time: 57.2, with caching: 8.17
            Parse time as % of pageload    3.3946587537, with caching: 0.63

3. http://www.youtube.com/shows - PageLoad time: 1287    , pageload time with caching: 1390
    http://s.ytimg.com/yt/cssbin/www-core-vflT2SXA2.css - ParseTime: 22.08, with caching: 0.19
    http://s.ytimg.com/yt/cssbin/www-the-rest-vflNb6rAI.css    - ParseTime: 1.04, with caching: 0.02
    http://s.ytimg.com/yt/cssbin/www-browse-new-vfl89j8Ia.css - ParseTime: 4.7, with caching: 0.21
                        Cumulative parsing time: 27.82, with caching: 0.43
            Parse time as % of pageload    2.1616161616, with caching: 0.03

4. http://www.youtube.com/shows/entertainment?feature=sh_c&pt=g&l=en - PageLoad time: 618, PLT with caching: 475
    http://s.ytimg.com/yt/cssbin/www-core-vflT2SXA2.css - ParseTime: 31.96, with caching: 0.17
    http://s.ytimg.com/yt/cssbin/www-the-rest-vflNb6rAI.css - ParseTime: 0.96, with caching: 0.01
    http://s.ytimg.com/yt/cssbin/www-browse-new-vfl89j8Ia.css - ParseTime: 5.29, with caching: 0.04
                        Cumulative parsing time: 38.21, with caching: 0.23
            Parse time as % of pageload    6.1828478964, with caching: 0.04

http://www.youtube.com/shows/news?feature=sh_c&pt=g&l=en - PageLoad time: 607 , with caching: 921
    http://s.ytimg.com/yt/cssbin/www-core-vflT2SXA2.css - ParseTime: 31.8, with caching: 0.33
    http://s.ytimg.com/yt/cssbin/www-the-rest-vflNb6rAI.css    - ParseTime: 1.04, with caching: 0.01
    http://s.ytimg.com/yt/cssbin/www-browse-vflXj985o.css - ParseTime: 4.3, with caching: 7.85
                        Cumulative parsing time: 37.14, with caching: 8.2
            Parse time as % of pageload    6.118616145, with caching: 0.89

http://www.youtube.com/trailers - PageLoad time: 856, PLT with caching: 919
    http://s.ytimg.com/yt/cssbin/www-core-vflT2SXA2.css - ParseTime: 44.11, with caching: 0.49
    http://s.ytimg.com/yt/cssbin/www-the-rest-vflNb6rAI.css    - ParseTime: 1.53, with caching: 0.04
    http://s.ytimg.com/yt/cssbin/www-browse-new-vfl89j8Ia.css - ParseTime: 9.38, with caching: 0.1
                        Cumulative parsing time: 55.02, with caching: 0.64
            Parse time as % of pageload    6.4275700935, with caching: 0.07

http://www.youtube.com/live    PageLoad time: 875, PLT with caching: 774    
    http://s.ytimg.com/yt/cssbin/www-core-vflT2SXA2.css - ParseTime: 21.34, with caching: 0.25
    http://s.ytimg.com/yt/cssbin/www-the-rest-vflNb6rAI.css    - ParseTime: 0.82, with caching: 0.02
    http://s.ytimg.com/yt/cssbin/www-browse-vflXj985o.css - ParseTime: 4.92, with caching: 0.05
                        Cumulative parsing time: 27.08, with caching: 0.32
            Parse as % of pageload    1.387295082, with cacing: 0.04

-- 
Configure bugmail: https://bugs.webkit.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the assignee for the bug.