read() performance - Linux.too?

[Unknown W. Brackets]

Derek,

Your question doesn't make complete sense to me, so I'm going to back up 
a bit.  Please forgive me if I patronize you, or fail to answer your 
question.

The garbage collector has "ranges" of memory it scans (as I'm completely 
sure you already know.)  For example, you could add an arbitrary range. 
  Consider:

void* p = malloc(100);
std.gc.addRange(p, p + cast(ptrdiff_t) 100);

This will cause it to scan the space between (p) and (p + 100) or 
pointers (roots.)  Removing a range does not mean, as far as I can see, 
that the memory it points to will never be freed; just that it will not 
be scanned.

An addRange() happens automatically when you new with the garbage collector.

-[Unknown]


> On Tue, 25 Jul 2006 17:18:24 +1200, Regan Heath wrote:
> 
>> On Tue, 25 Jul 2006 15:15:24 +1000, Derek Parnell  
>> <derek at nomail.afraid.org> wrote:
>>> On Mon, 24 Jul 2006 22:02:31 -0700, Unknown W. Brackets wrote:
>>>
>>>> Actually, I believe it's just:
>>>>
>>>> import std.gc;
>>>>
>>>> // ...
>>>>
>>>> ubyte[] data = new ubyte[1024 * 1024];
>>>> std.gc.removeRange(data);
>>>>
>>>> This tells it, afaik, not to scan the described range for pointers.  It
>>>> seems to me entirely possible that the compiler could automatically
>>>> generate this code for new ubyte[] and such calls.
>>> Yes, but wouldn't that RAM be deallocated only at program end? If you
>>> wanted it deallocated earlier you would still have to delete it.
>> The range pointed at by the array 'data' shouldn't be scanned, but there  
>> is no reason the array reference itself cannot be scanned and therefore  
>> collected, right? And if the array reference is collected, the data will  
>> be freed, just not scanned for other pointers, right?
> 
> Yes that sort of makes sense. So does the parameter stack get scanned after
> a function returns but before the calling function takes control again,
> because that's where the array reference resides usually. Or is it that
> when a 'new' is done, the returned address is added to a list that the GC
> uses to free up RAM from? 
>