[webkit-dev] squirrelfish-bytecode

[Rob Kroeger]

Hi,

On Wednesday, May 13, 2009, Jeremy Orlow <jorlow at chromium.org> wrote:
> On Wed, May 13, 2009 at 1:11 AM, Maciej Stachowiak <mjs at apple.com> wrote:
>
>
> On May 13, 2009, at 12:18 AM, Meryl Silverburgh wrote:
>
>
> Hi,
>
> Does webkit cache squirrelfish bytecode? For example, multiple can use
> the same javascript file (e.g. common javascript libraries, like
> jquery, or same domain uses some common javascript file across
> different pages for the same domain).
>
> When webkit parses the JS file and builds squirrelfish-bytecode,  does
> it cache it ? so that subsequence loading of the same js file will
> skip the js compile process?
>
>
>
> We don't currently cache the bytecode (or the native code). It is an option we have considered, however, currently, code generation is a trivial portion of JS execution time (< 2%), so we're not pursuing this at the moment.
>
>
> What does the < 2% number reflect?  The percent of time while running a particular benchmark or something?
> I totally believe that the speed of runtime is not really affected by it, but what about page load latency?  Compile time is a non-trivial component of load time for most JIT compilers I've heard of.

[Speaking from the point of view of my day job working on Mobile Gmail
instead of occasional evening webkit hacker]

Performance tests on mobile gmail for iPhone show that the time from
loading the first few bytes of the page from AppCache to the
completion of executing the "static" JavaScript (function and variable
definitions) occupies a large portion of the application startup time.
Somehow speeding this up (caching the parsed and compiled version of
JavaScript stored in AppCache maybe?) would be a huge benefit to
complex web applications.

Rob.

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-- 
Rob Kroeger
rjkroege at liqui.org
http://www.liqui.org