Re: [PATCH 1/1] mm: vmscan: Reduce throttling due to a failure to make progress

Mike Galbraith
2021-11-30T18:00:28Z

On Tue, 2021-11-30 at 17:27 +0000, Mel Gorman wrote:
>
> Obviously a fairly different experience and most likely due to the
> underlying storage.

I bet a virtual nickle this is the sore spot.

---
mm/vmscan.c | 10 ++++++++++
1 file changed, 10 insertions(+)

--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3360,7 +3360,17 @@ static void shrink_node(pg_data_t *pgdat
if (!current_is_kswapd() && current_may_throttle() &&
!sc->hibernation_mode &&
test_bit(LRUVEC_CONGESTED, &target_lruvec->flags))
+#if 0
reclaim_throttle(pgdat, VMSCAN_THROTTLE_WRITEBACK);
+#else
+ /*
+ * wait_iff_congested() used to live here and was
+ * _apparently_ a misspelled cond_resched()?????
+ * In any case, we are most definitely NOT starting
+ * any IO in reclaim_throttle(), so why bother?
+ */
+ cond_resched();
+#endif

if (should_continue_reclaim(pgdat, sc->nr_reclaimed -
nr_reclaimed,
sc))