On Wed, Dec 19, 2012 at 04:08:05PM -0800, Andrew Morton wrote:
> On Mon, 17 Dec 2012 13:12:35 -0500
> Johannes Weiner <han...@cmpxchg.org> wrote:
>
> > Reclaim pressure balance between anon and file pages is calculated
> > through a tuple of numerators and a shared denominator.
> >
> > Exceptional cases that want to force-scan anon or file pages configure
> > the numerators and denominator such that one list is preferred, which
> > is not necessarily the most obvious way:
> >
> > fraction[0] = 1;
> > fraction[1] = 0;
> > denominator = 1;
> > goto out;
> >
> > Make this easier by making the force-scan cases explicit and use the
> > fractionals only in case they are calculated from reclaim history.
> >
> > And bring the variable declarations/definitions in order.
> >
> > ...
> >
> > + u64 fraction[2], uninitialized_var(denominator);
>
> Using uninitialized_var() puts Linus into rant mode. Unkindly, IMO:
> uninitialized_var() is documentarily useful and reduces bloat. There is
> a move afoot to replace it with
>
> int foo = 0; /* gcc */
>
> To avoid getting ranted at we can do
>
> --- a/mm/vmscan.c~mm-vmscan-clean-up-get_scan_count-fix
> +++ a/mm/vmscan.c
> @@ -1658,7 +1658,8 @@ static void get_scan_count(struct lruvec
> unsigned long *nr)
> {
> struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
> - u64 fraction[2], uninitialized_var(denominator);
> + u64 fraction[2];
> + u64 denominator = 0;
> struct zone *zone = lruvec_zone(lruvec);
> unsigned long anon_prio, file_prio;
> enum scan_balance scan_balance;
Makes sense, I guess, but then you have to delete this line from the
changelog:
"And bring the variable declarations/definitions in order."
Or change it to "partial" order or something... :-)
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