And what if they don't live in the nursery?
On Aug 24, 2010, at 10:51 AM, Kevin Tew wrote:
Write barriers in racket3m are implemented using memory protection primitives
provided by the OS.
Between collections we only incur a write barrier cost the first time a page
(16k in racket) is
On Aug 24, 2010, at 10:46 AM, Matthias Felleisen wrote:
(I don't quite understand why there's no extra cost for the second access,
but I'll think about it and figure it out.)
If I understand things correctly, the short answer is fancy hardware. The
page is marked as read-only in the MMU, so
On Tue, Aug 24, 2010 at 11:43 AM, Kevin Tew t...@cs.utah.edu wrote:
After a garbage collection all non-nursery memory is write-protected.
The first write to a page (16kB) , after a garbage collection, incurs the
cost of unprotecting the page so it is writable and recording that the page
has
What documentation are you looking at?
http://docs.racket-lang.org/htdp-langs/advanced-prim-ops.html#(part._(lib._htdp-advanced..ss._lang)._.Hash_.Tables)
As far as the immutable functions, when I sent you the list of the
functions I intended to add, those were not on it. They were
intentionally
On 08/24/2010 11:38 AM, Jay McCarthy wrote:
On Tue, Aug 24, 2010 at 10:53 AM, Joe Marshalljmarsh...@alum.mit.edu wrote:
I'm surprised that racket3m uses page protection. Taking a hardware trap
can often be thousands of times slower than taking an inline conditional
branch.
My
So at this point, we don't really know what the relative costs are. -- Matthias
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Oh yeah, that's what I figured (and why there was such a long delay
before my change), but I thought I'd reply here since that's where
this came up most recently.
Robby
On Tue, Aug 24, 2010 at 9:56 AM, Laurent laurent.ors...@gmail.com wrote:
On Tue, Aug 24, 2010 at 16:46, Robby Findler
Here's a program that tries to expose various costs.
On my machine, the output is:
'cons-of-cXr+barrier-set!
cpu time: 13137 real time: 13206 gc time: 552
'cons-of-cXr+free-set!
cpu time: 12832 real time: 12995 gc time: 541
'cons-of-cXr
cpu time: 10023 real time: 10103 gc time: 526
On Aug 24, 2010, at 7:13 PM, Matthew Flatt wrote:
When the GC is well-tuned, it's difficult to slow a program down by
using mutation --- especially relative to all the other ways you can
slow a program down.
This is good enough for me to correct my old belief about mutation and GCing.
There is not now but we could make a module that only exported them so you
could provide all-from-out it and thus centralize the list of subforms. That's
the cleanest idea I have. (You don't want to hear my really bad ideas)
Jay
Sent from my iPhone
On Aug 24, 2010, at 8:46 PM, Shriram
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