[PATCH 3/3] mm: memdelay: drop IO as productive time

[Johannes Weiner]

Counting IO as productive time distorts the sense of pressure with
workloads that are naturally IO-bound. Memory pressure can cause IO,
and thus cause "productive" IO to slow down - yet we don't attribute
this slowdown properly to a shortage of memory.

Disregard IO time altogether, and use CPU time alone as the baseline.

Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
---
 mm/memdelay.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/mm/memdelay.c b/mm/memdelay.c
index ea5ede79f044..fbce1d4ba142 100644
--- a/mm/memdelay.c
+++ b/mm/memdelay.c
@@ -113,12 +113,11 @@ static void domain_cpu_update(struct memdelay_domain *md, int cpu,
 	 * one running the workload, the domain is considered fully
 	 * blocked 50% of the time.
 	 */
-	if (mdc->tasks[MTS_DELAYED_ACTIVE] && !mdc->tasks[MTS_IOWAIT])
+	if (mdc->tasks[MTS_DELAYED_ACTIVE])
 		state = MDS_FULL;
 	else if (mdc->tasks[MTS_DELAYED])
-		state = (mdc->tasks[MTS_RUNNABLE] || mdc->tasks[MTS_IOWAIT]) ?
-			MDS_PART : MDS_FULL;
-	else if (mdc->tasks[MTS_RUNNABLE] || mdc->tasks[MTS_IOWAIT])
+		state = mdc->tasks[MTS_RUNNABLE] ? MDS_PART : MDS_FULL;
+	else if (mdc->tasks[MTS_RUNNABLE])
 		state = MDS_NONE;
 	else
 		state = MDS_IDLE;
-- 
2.14.2


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