From 38cf04b8887cddd3ecb1317323c5ec08d392536e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C5=81ukasz=20Magiera?= <magik6k@gmail.com>
Date: Wed, 29 Apr 2020 16:04:05 +0200
Subject: [PATCH] sched: prefer workers with lower utilization

---
 sched.go             | 22 +++++++++++++++++++++-
 selector_alloc.go    |  2 +-
 selector_existing.go |  2 +-
 selector_task.go     |  2 +-
 4 files changed, 24 insertions(+), 4 deletions(-)

diff --git a/sched.go b/sched.go
index ffaad211d..ad3c948dd 100644
--- a/sched.go
+++ b/sched.go
@@ -194,6 +194,8 @@ func (sh *scheduler) maybeSchedRequest(req *workerRequest) (bool, error) {
 	tried := 0
 	var acceptable []WorkerID
 
+	needRes := ResourceTable[req.taskType][sh.spt]
+
 	for wid, worker := range sh.workers {
 		ok, err := req.sel.Ok(req.ctx, req.taskType, worker)
 		if err != nil {
@@ -205,7 +207,6 @@ func (sh *scheduler) maybeSchedRequest(req *workerRequest) (bool, error) {
 		}
 		tried++
 
-		needRes := ResourceTable[req.taskType][sh.spt]
 		if !canHandleRequest(needRes, sh.spt, wid, worker.info.Resources, worker.preparing) {
 			continue
 		}
@@ -384,6 +385,25 @@ func canHandleRequest(needRes Resources, spt abi.RegisteredProof, wid WorkerID,
 	return true
 }
 
+func (a *activeResources) utilization(wr storiface.WorkerResources) float64 {
+	var max float64
+
+	cpu := float64(a.cpuUse) / float64(wr.CPUs)
+	max = cpu
+
+	memMin := float64(a.memUsedMin + wr.MemReserved) / float64(wr.MemPhysical)
+	if memMin > max {
+		max = memMin
+	}
+
+	memMax := float64(a.memUsedMax + wr.MemReserved) / float64(wr.MemPhysical + wr.MemSwap)
+	if memMax > max {
+		max = memMax
+	}
+
+	return max
+}
+
 func (sh *scheduler) schedNewWorker(w *workerHandle) {
 	sh.workersLk.Lock()
 	defer sh.workersLk.Unlock()
diff --git a/selector_alloc.go b/selector_alloc.go
index 1ceab0ecb..c7d06a7bc 100644
--- a/selector_alloc.go
+++ b/selector_alloc.go
@@ -53,7 +53,7 @@ func (s *allocSelector) Ok(ctx context.Context, task sealtasks.TaskType, whnd *w
 }
 
 func (s *allocSelector) Cmp(ctx context.Context, task sealtasks.TaskType, a, b *workerHandle) (bool, error) {
-	return a.info.Hostname > b.info.Hostname, nil // TODO: Better strategy
+	return a.active.utilization(a.info.Resources) < b.active.utilization(b.info.Resources), nil
 }
 
 var _ WorkerSelector = &allocSelector{}
diff --git a/selector_existing.go b/selector_existing.go
index eccdefbf2..46dd3278e 100644
--- a/selector_existing.go
+++ b/selector_existing.go
@@ -54,7 +54,7 @@ func (s *existingSelector) Ok(ctx context.Context, task sealtasks.TaskType, whnd
 }
 
 func (s *existingSelector) Cmp(ctx context.Context, task sealtasks.TaskType, a, b *workerHandle) (bool, error) {
-	return a.info.Hostname > b.info.Hostname, nil // TODO: Better strategy
+	return a.active.utilization(a.info.Resources) < b.active.utilization(b.info.Resources), nil
 }
 
 var _ WorkerSelector = &existingSelector{}
diff --git a/selector_task.go b/selector_task.go
index 5e67ad665..2f20f9a28 100644
--- a/selector_task.go
+++ b/selector_task.go
@@ -40,7 +40,7 @@ func (s *taskSelector) Cmp(ctx context.Context, _ sealtasks.TaskType, a, b *work
 		return len(atasks) < len(btasks), nil // prefer workers which can do less
 	}
 
-	return a.info.Hostname > b.info.Hostname, nil // TODO: Better fallback strategy
+	return a.active.utilization(a.info.Resources) < b.active.utilization(b.info.Resources), nil
 }
 
 var _ WorkerSelector = &allocSelector{}