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adjust Guide to warn about performance measurement in DrRacket

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This commit is contained in:
Matthew Flatt 2011-05-24 08:02:09 -06:00
parent 0aefb8d43c
commit 00e17ab51f
2 changed files with 29 additions and 0 deletions
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24
collects/scribblings/guide/performance.scrbl
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@ -5,6 +5,9 @@
@title[#:tag "performance"]{Performance} @title[#:tag "performance"]{Performance}
@section-index["benchmarking"]
@section-index["speed"]
Alan Perlis famously quipped ``Lisp programmers know the value of Alan Perlis famously quipped ``Lisp programmers know the value of
everything and the cost of nothing.'' A Racket programmer knows, for everything and the cost of nothing.'' A Racket programmer knows, for
example, that a @racket[lambda] anywhere in a program produces a value example, that a @racket[lambda] anywhere in a program produces a value
@ -20,6 +23,27 @@ and memory performance of Racket code.
@; ---------------------------------------------------------------------- @; ----------------------------------------------------------------------
@section[#:tag "DrRacket-perf"]{Performance in DrRacket}
By default, DrRacket instruments programs for debugging, and
debugging instrumentation can significantly degrade performance for
some programs. Even when debugging is disabled through the
@onscreen{Choose Language...} dialog's @onscreen{Show Details} panel,
the @onscreen{Preserve stacktrace} checkbox is clicked by default,
which also affects performance. Disabling debugging and stacktrace
preservation provides performance results that are more consistent
with running in plain @exec{racket}.
Even so, DrRacket and programs developed within DrRacket use the same
Racket virtual machine, so garbage collection times (see
@secref["gc-perf"]) may be longer in DrRacket than when a program is
run by itself, and DrRacket threads may impede execution of program
threads. For the most reliable timing results for a program, run in
plain @exec{racket} instead of in the DrRacket development
environment.
@; ----------------------------------------------------------------------
@section[#:tag "JIT"]{The Bytecode and Just-in-Time (JIT) Compilers} @section[#:tag "JIT"]{The Bytecode and Just-in-Time (JIT) Compilers}
Every definition or expression to be evaluated by Racket is compiled Every definition or expression to be evaluated by Racket is compiled

5
collects/typed-scheme/scribblings/optimization.scrbl
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@ -12,6 +12,11 @@ Typed Racket provides a type-driven optimizer that rewrites well-typed
programs to potentially make them faster. It should in no way make programs to potentially make them faster. It should in no way make
your programs slower or unsafe. your programs slower or unsafe.
@margin-note{For general information Racket performance and
benchmarking, see @secref[#:doc '(lib
"scribblings/guide/guide.scrbl")]{performance}.}
@section{Turning the optimizer off} @section{Turning the optimizer off}
Typed Racket's optimizer is turned on by default. If you want to Typed Racket's optimizer is turned on by default. If you want to