On Tue, Oct 9, 2012 at 4:21 AM, Maciej Stachowiak <m...@apple.com> wrote:
> One preliminary finding of ours is that different web pages fairly often > load identical resource bodies from different URLs. We expect possible > benefits from sharing the body data of resources in memory even if we > cannot share the URL or response headers. > I did some preliminary profiling of this earlier. The data is not necessarily very representative of the web as whole, I simply browsed through a number of popular sites with an instrumented build ( https://bug-98539-attachments.webkit.org/attachment.cgi?id=167753). Here is what I had in the WebCore memory cache in the end: TOTAL duplicates count=443 size=852791 decodedSize=3426638 all cached resources count=2636 size=116463712 17% of cache entries are exact copies of previous entries. They use 4.3MB out of total 116MB cache size (4%). The average size of duplicate entries is much smaller than the average entry size (not surprisingly, transparent 1x1 images etc). Some examples: HTTP vs. HTTPS: hash=5d90af size=91556 decodedSize=34834 https://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js hash=5d90af size=91556 decodedSize=32 http://ajax.googleapis.com/ajax/libs/jquery/1.6.2/jquery.min.js (decodedSize for js resources is the size of the function offset cache which can differ depending which functions have been parsed). Ad scripts with deliberately unique URLs: hash=6f6494 size=3111 decodedSize=32 http://ad.doubleclick.net/adj/teg.fmsq/j2ek;subs=n;wsub=n;sdn=n;dcopt=ist;pos=ldr_top;sz=728x90,970x90;tile=1;ord=76273718 ? hash=6f6494 size=3111 decodedSize=648 http://ad.doubleclick.net/adj/teg.fmsq/j2ek;subs=n;wsub=n;sdn=n;dcopt=ist;pos=ldr_top;sz=728x90,970x90;tile=1;ord=711567314 ? hash=6f6494 size=3111 decodedSize=32 http://ad.doubleclick.net/adj/teg.fmsq/j2ek;subs=n;wsub=n;sdn=n;dcopt=ist;pos=ldr_top;sz=728x90,970x90;tile=1;ord=908690779 ? hash=6f6494 size=3111 decodedSize=32 http://ad.doubleclick.net/adj/teg.fmsq/j2ek;subs=n;wsub=n;sdn=n;dcopt=ist;pos=ldr_top;sz=728x90,970x90;tile=1;ord=876087584 ? Same framework loaded by multiple unrelated sites: hash=230c7d size=1958 decodedSize=0 http://static.iltalehti.fi/js/measure/spring.js hash=230c7d size=1958 decodedSize=1536 http://yle.fi/global/spring/spring.js (didn't see as many of these as expected though i'm sure there are sites that run into this) Copy-paste resources: hash=8fb3e size=3965 decodedSize=13088 http://store.storeimages.cdn-apple.com/2149/store.apple.com/rs/source/store/base/nav/globalnav/css/bg/globalsearch_spinner.gif hash=8fb3e size=3965 decodedSize=13088 http://store.storeimages.cdn-apple.com/2150/store.apple.com/rs/source/store/features/search/css/bg/spinner.gif hash=8fb3e size=3965 decodedSize=13088 http://store.storeimages.cdn-apple.com/2150/store.apple.com/rs/source/store/base/nav/globalnav/css/bg/globalsearch_spinner.gif hash=8fb3e size=3965 decodedSize=13088 http://images.apple.com/global/nav/images/globalsearch_spinner.gif Versioning: hash=cecbad size=184899 decodedSize=0 http://store.storeimages.cdn-apple.com/2150/store.apple.com/rs/applestore-rs-2.css hash=cecbad size=184899 decodedSize=0 http://store.storeimages.cdn-apple.com/2149/store.apple.com/rs/applestore-rs-2.css hash=47a8de size=20041 decodedSize=7870 http://js.t.sinajs.cn/open/analytics/js/suda.js?version=b4d67909ad6b5b7d hash=47a8de size=20041 decodedSize=7870 http://tjs.sjs.sinajs.cn/open/analytics/js/suda.js Multiple content servers: hash=8e976b size=808 decodedSize=13088 http://i0.sinaimg.cn/home/deco/2008/0329/sinahome_0803_ws_003_new.gif hash=8e976b size=808 decodedSize=71700 http://i3.sinaimg.cn/home/deco/2008/0329/sinahome_0803_ws_003_new.gif Based on this I think this is definitely worth at least looking further. antti You can also expect that we won't push forward blindly on this effort if > data ultimately shows it to be a bad idea, or in general not worth the > complexity. > > Regards, > Maciej > > _______________________________________________ > webkit-dev mailing list > webkit-dev@lists.webkit.org > http://lists.webkit.org/mailman/listinfo/webkit-dev >
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