Re: [PATCH 06/10] mm: vmscan: Have kswapd writeback pages based ondirty pages encountered, not priority

From: Mel Gorman
Date: Sun Mar 17 2013 - 11:12:02 EST


On Sun, Mar 17, 2013 at 07:42:39AM -0700, Andi Kleen wrote:
> Mel Gorman <mgorman@xxxxxxx> writes:
>
> > @@ -495,6 +495,9 @@ typedef enum {
> > ZONE_CONGESTED, /* zone has many dirty pages backed by
> > * a congested BDI
> > */
> > + ZONE_DIRTY, /* reclaim scanning has recently found
> > + * many dirty file pages
> > + */
>
> Needs a better name. ZONE_DIRTY_CONGESTED ?
>

That might be confusing. The underlying BDI is not necessarily
congested. I accept your point though and will try thinking of a better
name.

> > + * currently being written then flag that kswapd should start
> > + * writing back pages.
> > + */
> > + if (global_reclaim(sc) && nr_dirty &&
> > + nr_dirty >= (nr_taken >> (DEF_PRIORITY - sc->priority)))
> > + zone_set_flag(zone, ZONE_DIRTY);
> > +
> > trace_mm_vmscan_lru_shrink_inactive(zone->zone_pgdat->node_id,
>
> I suppose you want to trace the dirty case here too.
>

I guess it wouldn't hurt to have a new tracepoint for when the flag gets
set. A vmstat might be helpful as well.

--
Mel Gorman
SUSE Labs
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