[vox-tech] can YOU be certified?!?

[Tim Riley]

Jeff Newmiller wrote:

> On Sun, 21 Jul 2002, Tim Riley wrote:
>
> > Peter Jay Salzman wrote:
> >
> > > begin ME <dugan@passwall.com>
> > > > On Sun, 21 Jul 2002, Peter Jay Salzman wrote:
> > > <snip>
> > >
> <snip>
> > Two weird things occurred when I ran this.
> >
> > First, the "top" command never showed
> > any swap space usage. Moreover, the
> > memory available never made it to zero.
> > It went from 28M down
> > to 18M before the malloc failed.
>
> Until you touch the pages involved, they do not become allocated.  Like
> holes in files.
>
> > Second and serendipitously, the bytes
> > allocated was 14 times more that the
> > total of memory and swap space.
> > (I have 64M memory and 72M
> > of swap (136M total), yet I was able to malloc
> > 1987M of memory.)
>
> malloc allocates some memory as overhead, and you wrote a bit more.  Thus,
> I would expect one 4096 byte page was physically allocated per
> buffer.  You allocated about 2034 buffers, so that racks up about 8M of
> touched memory.

> Either two pages are actually allocated (8M*2=16M < 18M) or the kernel is
> trying to keep some spare memory around.

Good answer, Jeff. Is this a great OS or what!?

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