lmkd: Speed up proc_get_heaviest() in one case am: e51c5fead2

Original change: https://android-review.googlesource.com/c/platform/system/memory/lmkd/+/3555666

Change-Id: Ifb142364dc85f1f5d5903332f53cbed556d7dbeb
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>

lmkd.cpp

diff --git a/lmkd.cpp b/lmkd.cpp
index 99f6b21..3cb458d 100644
--- a/lmkd.cpp
+++ b/lmkd.cpp
@@ -2234,6 +2234,10 @@
     struct adjslot_list *curr = head->next;
     struct proc *maxprocp = NULL;
     int maxsize = 0;
+    if ((curr != head) && (curr->next == head)) {
+        // Our list only has one process.  No need to access procfs for its size.
+        return (struct proc *)curr;
+    }
     while (curr != head) {
         int pid = ((struct proc *)curr)->pid;
         int tasksize = proc_get_size(pid);