Re: [HACKERS] \dt and disk access

On Sun, 22 Jun 1997, Bruce Momjian wrote:

> >     okay, I'm not totally familiary with palloc()...I did a project while
> > back where we mmap()'d a region of memory so that we didn't need to write
> > to disk.  Essentially, I used ftruncate() to create the size of the buffer I
> > wanted to mmap(), and never flushed the memory...
> >
> >     Not sure what palloc() does though...should look into it, eh? :(
>
> palloc() basically malloc's from a pool that gets auto-free'd at the end
> of statements or transcations.
>
> We could us mmap(), but why bother if we can just malloc() all the
> memory we need?  That is what has me confused.  Anyone know an advantage
> to using mmap() when you really don't want the image on disk?

    Okay...this is something I never truly have every succeeded in doing,
and do agree that it would be better then mmap()...mmap() is good when
multiple processes want/need to access the same memory, and, from what I've
seen, sort of acts as an intermediary between a malloc() and shmem()...

    Now I understand what you are thinking :)


Marc G. Fournier
Systems Administrator @ hub.org
primary: scrappy@hub.org           secondary: scrappy@{freebsd|postgresql}.org

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