Messages in this thread | | | Date | Tue, 26 Apr 2011 22:30:59 +1000 | From | NeilBrown <> | Subject | Re: [PATCH 12/13] mm: Throttle direct reclaimers if PF_MEMALLOC reserves are low and swap is backed by network storage |
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On Tue, 26 Apr 2011 08:36:53 +0100 Mel Gorman <mgorman@suse.de> wrote:
> +/* > + * Throttle direct reclaimers if backing storage is backed by the network > + * and the PFMEMALLOC reserve for the preferred node is getting dangerously > + * depleted. kswapd will continue to make progress and wake the processes > + * when the low watermark is reached > + */ > +static void throttle_direct_reclaim(gfp_t gfp_mask, struct zonelist *zonelist, > + nodemask_t *nodemask) > +{ > + struct zone *zone; > + int high_zoneidx = gfp_zone(gfp_mask); > + DEFINE_WAIT(wait); > + > + /* Check if the pfmemalloc reserves are ok */ > + first_zones_zonelist(zonelist, high_zoneidx, NULL, &zone); > + prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait, > + TASK_INTERRUPTIBLE); > + if (pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx)) > + goto out; > + > + /* Throttle */ > + do { > + schedule(); > + finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait); > + prepare_to_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait, > + TASK_INTERRUPTIBLE); > + } while (!pfmemalloc_watermark_ok(zone->zone_pgdat, high_zoneidx) && > + !fatal_signal_pending(current)); > + > +out: > + finish_wait(&zone->zone_pgdat->pfmemalloc_wait, &wait); > +}
You are doing an interruptible wait, but only checking for fatal signals. So if a non-fatal signal arrives, you will busy-wait.
So I suspect you want TASK_KILLABLE, so just use:
wait_event_killable(zone->zone_pgdat->pfmemalloc_wait, pgmemalloc_watermark_ok(zone->zone_pgdata, high_zoneidx));
(You also have an extraneous call to finish_wait)
NeilBrown
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