At 13.43 09/12/00 +0100, Rasmus Andersen wrote:
>On Sat, Dec 09, 2000 at 11:25:09AM +0100, Roberto Fichera wrote:
>[...]
> > >+ spin_lock(&mm->page_table_lock);
> > > mm->rss++;
> > >+ spin_unlock(&mm->page_table_lock);
> > >
> >
> > [...snip...]
> >
> > Why we couldn't use atomic_inc(&mm->rss) here and below, avoiding to wrap
> > the inc with a spin_lock()/spin_unlock() ?
> >
>
>AFAIR, because for some architectures we can't rely on mm->rss fitting in
>an atomic_t. See davem's (somewhat short) post in this thread. Otherwise
>search the archives for the original thread treating this problem.
and At 04.32 09/12/00 -0800, David S. Miller wrote:
> Date: Sat, 09 Dec 2000 11:25:09 +0100
> From: Roberto Fichera <kernel@tekno-soft.it>
>
> Why we couldn't use atomic_inc(&mm->rss) here and below, avoiding to wrap
> the inc with a spin_lock()/spin_unlock() ?
>
>atomic_t does not guarentee a large enough range necessary for mm->rss
If we haven't some atomic_t that can be negative we could define atomic_t
as unsigned long for all arch,
this is sufficient to fitting all the range for the mm->rss.
Roberto Fichera.
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