commit 48135c4cba933c9d74021fe994de7a9b2e116630
author Suren Baghdasaryan <surenb@google.com> Tue May 19 12:59:18 2020 -0700
committer Suren Baghdasaryan <surenb@google.com> Wed May 20 12:22:07 2020 -0700
tree b7550071f169bd922a93c102be29ea715918a1ca
parent fb1f592602282b7a89292263eef809caa239811a

lmkd: Do not kill perceptible apps due to low swap if above min wmark

Prevent kills of perceptible apps due to swap shortages unless system
free memory is below the min watermark. This prevents kills of important
apps when the system is recovering from the memory pressure.

Bug: 155709603
Test: memory stress test with multiple foreground apps
Signed-off-by: Suren Baghdasaryan <surenb@google.com>
Change-Id: I6beb4b55f8b4f7bc22818b5a7bdfa3adc6cd31c1

lmkd.cpp

diff --git a/lmkd.cpp b/lmkd.cpp
index 29bbc9a..8cef9f1 100644
--- a/lmkd.cpp
+++ b/lmkd.cpp
@@ -2396,12 +2396,20 @@
         snprintf(kill_desc, sizeof(kill_desc), "device is low on swap (%" PRId64
             "kB < %" PRId64 "kB) and thrashing (%" PRId64 "%%)",
             mi.field.free_swap * page_k, swap_low_threshold * page_k, thrashing);
+        /* Do not kill perceptible apps unless below min watermark */
+        if (wmark < WMARK_LOW) {
+            min_score_adj = PERCEPTIBLE_APP_ADJ + 1;
+        }
     } else if (swap_is_low && wmark < WMARK_HIGH) {
         /* Both free memory and swap are low */
         kill_reason = LOW_MEM_AND_SWAP;
         snprintf(kill_desc, sizeof(kill_desc), "%s watermark is breached and swap is low (%"
             PRId64 "kB < %" PRId64 "kB)", wmark > WMARK_LOW ? "min" : "low",
             mi.field.free_swap * page_k, swap_low_threshold * page_k);
+        /* Do not kill perceptible apps unless below min watermark */
+        if (wmark < WMARK_LOW) {
+            min_score_adj = PERCEPTIBLE_APP_ADJ + 1;
+        }
     } else if (wmark < WMARK_HIGH && swap_util_max < 100 &&
                (swap_util = calc_swap_utilization(&mi)) > swap_util_max) {
         /*