Re: Getting the file name from a FILE *

Richard Tobin wrote:
> In article <KbCdnebxjomgvvXV4p2dnAA@[EMAIL PROTECTED]
>,
> Tor Rustad  <bwzcab@[EMAIL PROTECTED]
> wrote:
> 
>>> Well, that would have been the natural interpretation, but in that
> 
>> Instead of assuming others write something stupid, it's perhaps wise to

>> reconsider your own smartness first.
> 
> I just couldn't see how your point made any sense otherwise.

In the message you responded to, I said:

"When adding features like _fname(), there will be a cost,
the main thing might not even the extra bloat by mem usage,
but that this trigger more cache misses, worse branch
prediction etc. etc."


To spell it out: my main consern was NOT the extra SPACE required, but 
the TIME overhead. Regardless, I would add a benchmark with at least 10 
000 files to open and read, considering only 100 files, was way too
little.


>>> case what would the problem be with storing the file names?  The
>>> amount of space required corresponds to the number of simultaneously
>>> open files, not the total number ever opened.
> 
>> FYI, an implementation of the standard C library free(), may or may not

>> trigger a system call, which actually free the memory chunk allocated. 
>> Even if a program burn memory like a pig, modern OS'es will typically 
>> swap out unused memory pages anyway.
> 
> I still don't understand your point.  I know all that.


IF you did, then please explain how this make sense:

"The amount of space required corresponds to the number of 
simultaneously open files, not the total number ever opened."


FYI, assume that a program open X files, load the content of all X 
files, then close X files.

At this point, the "simultaneously open files" are only 3. If free() 
implementation has no explicit system call to free the space allocated, 
the memory required by the program at this point, does _not_ correspond 
to 3 files, but to

3 + X

files.

>> If the free() implementation is like you suggest, with an explicit 
>> system call for every free() call.
> 
> I haven't suggested anything like that at all.  I doubt there are
> any such implementations.

This statement

"The amount of space required corresponds to the number of 
simultaneously open files, not the total number ever opened."

only made sense to me, IF you suggested exactly that. Unlike others, I 
do assume that people are smart. :P

-- 
Tor <echo bwzcab@[EMAIL PROTECTED]
 | tr i-za-h a-z>