lmkd: adjust thrashing dection strategy am: 1f72f5fa4b am: 58f6be8f3c am: c587b2629c
Original change: https://android-review.googlesource.com/c/platform/system/memory/lmkd/+/1414468
Change-Id: Ie55859692029d3946bf35a3b9fcfe692d14a25da
diff --git a/lmkd.cpp b/lmkd.cpp
index b258f27..9508b5a 100644
--- a/lmkd.cpp
+++ b/lmkd.cpp
@@ -100,6 +100,7 @@
#define EIGHT_MEGA (1 << 23)
#define TARGET_UPDATE_MIN_INTERVAL_MS 1000
+#define THRASHING_RESET_INTERVAL_MS 1000
#define NS_PER_MS (NS_PER_SEC / MS_PER_SEC)
#define US_PER_MS (US_PER_SEC / MS_PER_SEC)
@@ -2315,16 +2316,18 @@
DIRECT_RECLAIM,
};
static int64_t init_ws_refault;
+ static int64_t prev_workingset_refault;
static int64_t base_file_lru;
static int64_t init_pgscan_kswapd;
static int64_t init_pgscan_direct;
static int64_t swap_low_threshold;
static bool killing;
- static int thrashing_limit;
- static bool in_reclaim;
+ static int thrashing_limit = thrashing_limit_pct;
static struct zone_watermarks watermarks;
static struct timespec wmark_update_tm;
static struct wakeup_info wi;
+ static struct timespec thrashing_reset_tm;
+ static int64_t prev_thrash_growth = 0;
union meminfo mi;
union vmstat vs;
@@ -2340,6 +2343,7 @@
bool cut_thrashing_limit = false;
int min_score_adj = 0;
int swap_util = 0;
+ long since_thrashing_reset_ms;
if (clock_gettime(CLOCK_MONOTONIC_COARSE, &curr_tm) != 0) {
ALOGE("Failed to get current time");
@@ -2378,6 +2382,8 @@
/* Reset file-backed pagecache size and refault amounts after a kill */
base_file_lru = vs.field.nr_inactive_file + vs.field.nr_active_file;
init_ws_refault = vs.field.workingset_refault;
+ thrashing_reset_tm = curr_tm;
+ prev_thrash_growth = 0;
}
/* Check free swap levels */
@@ -2396,22 +2402,50 @@
} else if (vs.field.pgscan_kswapd > init_pgscan_kswapd) {
init_pgscan_kswapd = vs.field.pgscan_kswapd;
reclaim = KSWAPD_RECLAIM;
- } else {
- in_reclaim = false;
- /* Skip if system is not reclaiming */
+ } else if (vs.field.workingset_refault == prev_workingset_refault) {
+ /* Device is not thrashing and not reclaiming, bail out early until we see these stats changing*/
goto no_kill;
}
- if (!in_reclaim) {
- /* Record file-backed pagecache size when entering reclaim cycle */
+ prev_workingset_refault = vs.field.workingset_refault;
+
+ /*
+ * It's possible we fail to find an eligible process to kill (ex. no process is
+ * above oom_adj_min). When this happens, we should retry to find a new process
+ * for a kill whenever a new eligible process is available. This is especially
+ * important for a slow growing refault case. While retrying, we should keep
+ * monitoring new thrashing counter as someone could release the memory to mitigate
+ * the thrashing. Thus, when thrashing reset window comes, we decay the prev thrashing
+ * counter by window counts. if the counter is still greater than thrashing limit,
+ * we preserve the current prev_thrash counter so we will retry kill again. Otherwise,
+ * we reset the prev_thrash counter so we will stop retrying.
+ */
+ since_thrashing_reset_ms = get_time_diff_ms(&thrashing_reset_tm, &curr_tm);
+ if (since_thrashing_reset_ms > THRASHING_RESET_INTERVAL_MS) {
+ long windows_passed;
+ /* Calculate prev_thrash_growth if we crossed THRASHING_RESET_INTERVAL_MS */
+ prev_thrash_growth = (vs.field.workingset_refault - init_ws_refault) * 100 / base_file_lru;
+ windows_passed = (since_thrashing_reset_ms / THRASHING_RESET_INTERVAL_MS);
+ /*
+ * Decay prev_thrashing unless over-the-limit thrashing was registered in the window we
+ * just crossed, which means there were no eligible processes to kill. We preserve the
+ * counter in that case to ensure a kill if a new eligible process appears.
+ */
+ if (windows_passed > 1 || prev_thrash_growth < thrashing_limit) {
+ prev_thrash_growth >>= windows_passed;
+ }
+
+ /* Record file-backed pagecache size when crossing THRASHING_RESET_INTERVAL_MS */
base_file_lru = vs.field.nr_inactive_file + vs.field.nr_active_file;
init_ws_refault = vs.field.workingset_refault;
+ thrashing_reset_tm = curr_tm;
thrashing_limit = thrashing_limit_pct;
} else {
/* Calculate what % of the file-backed pagecache refaulted so far */
thrashing = (vs.field.workingset_refault - init_ws_refault) * 100 / base_file_lru;
}
- in_reclaim = true;
+ /* Add previous cycle's decayed thrashing amount */
+ thrashing += prev_thrash_growth;
/*
* Refresh watermarks once per min in case user updated one of the margins.
@@ -2428,7 +2462,7 @@
calc_zone_watermarks(&zi, &watermarks);
wmark_update_tm = curr_tm;
- }
+ }
/* Find out which watermark is breached if any */
wmark = get_lowest_watermark(&mi, &watermarks, swap_is_low ? 115 : 100);
