From a54de1835bdf1516905e500143ff3f8522ab5e27 Mon Sep 17 00:00:00 2001
From: Archana Shinde <archana.m.shinde@intel.com>
Date: Wed, 28 Mar 2018 16:12:31 -0700
Subject: [PATCH 1/2] iothread: Add ability to configure iothreads

IOthreads also known as x-data-plane allow IO to
be processed in a separate thread rather than the main event
loop. This produces much better IO throughput and latency.

Signed-off-by: Archana Shinde <archana.m.shinde@intel.com>
---
 qemu/qemu.go      | 17 +++++++++++++++++
 qemu/qemu_test.go | 14 ++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/qemu/qemu.go b/qemu/qemu.go
index 89d053fe95..0b5adb2858 100644
--- a/qemu/qemu.go
+++ b/qemu/qemu.go
@@ -1159,6 +1159,11 @@ type Knobs struct {
 	Realtime bool
 }
 
+// IOThread allows IO to be performed on a separate thread.
+type IOThread struct {
+	ID string
+}
+
 // Config is the qemu configuration structure.
 // It allows for passing custom settings and parameters to the qemu API.
 type Config struct {
@@ -1213,6 +1218,8 @@ type Config struct {
 	// fds is a list of open file descriptors to be passed to the spawned qemu process
 	fds []*os.File
 
+	IOThreads []IOThread
+
 	qemuParams []string
 }
 
@@ -1481,6 +1488,15 @@ func (config *Config) appendBios() {
 	}
 }
 
+func (config *Config) appendIOThreads() {
+	for _, t := range config.IOThreads {
+		if t.ID != "" {
+			config.qemuParams = append(config.qemuParams, "-object")
+			config.qemuParams = append(config.qemuParams, fmt.Sprintf("iothread,id=%s", t.ID))
+		}
+	}
+}
+
 // LaunchQemu can be used to launch a new qemu instance.
 //
 // The Config parameter contains a set of qemu parameters and settings.
@@ -1504,6 +1520,7 @@ func LaunchQemu(config Config, logger QMPLog) (string, error) {
 	config.appendKnobs()
 	config.appendKernel()
 	config.appendBios()
+	config.appendIOThreads()
 
 	if err := config.appendCPUs(); err != nil {
 		return "", err
diff --git a/qemu/qemu_test.go b/qemu/qemu_test.go
index b7e60e7271..1c63e42bdb 100644
--- a/qemu/qemu_test.go
+++ b/qemu/qemu_test.go
@@ -67,6 +67,10 @@ func testAppend(structure interface{}, expected string, t *testing.T) {
 	case RTC:
 		config.RTC = s
 		config.appendRTC()
+
+	case IOThread:
+		config.IOThreads = []IOThread{s}
+		config.appendIOThreads()
 	}
 
 	result := strings.Join(config.qemuParams, " ")
@@ -525,3 +529,13 @@ func TestAppendRTC(t *testing.T) {
 
 	testAppend(rtc, rtcString, t)
 }
+
+var ioThreadString = "-object iothread,id=iothread1"
+
+func TestAppendIOThread(t *testing.T) {
+	ioThread := IOThread{
+		ID: "iothread1",
+	}
+
+	testAppend(ioThread, ioThreadString, t)
+}

From 9130f375166febfa9ca1937d126d2c6aa155b2a1 Mon Sep 17 00:00:00 2001
From: Archana Shinde <archana.m.shinde@intel.com>
Date: Wed, 28 Mar 2018 16:15:52 -0700
Subject: [PATCH 2/2] scsi: Allow scsi controller to associate with an IO
 thread.

This enable data-plane for scsi. All drives attached to the
scsi controller will have their IO processed in a single separate
IO thread instead of qemu's main event loop.

Signed-off-by: Archana Shinde <archana.m.shinde@intel.com>
---
 qemu/qemu.go      | 6 ++++++
 qemu/qemu_test.go | 3 ++-
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/qemu/qemu.go b/qemu/qemu.go
index 0b5adb2858..4b0e41795a 100644
--- a/qemu/qemu.go
+++ b/qemu/qemu.go
@@ -841,6 +841,9 @@ type SCSIController struct {
 
 	// DisableModern prevents qemu from relying on fast MMIO.
 	DisableModern bool
+
+	// IOThread is the IO thread on which IO will be handled
+	IOThread string
 }
 
 // Valid returns true if the SCSIController structure is valid and complete.
@@ -867,6 +870,9 @@ func (scsiCon SCSIController) QemuParams(config *Config) []string {
 	if scsiCon.DisableModern {
 		devParams = append(devParams, fmt.Sprintf("disable-modern=true"))
 	}
+	if scsiCon.IOThread != "" {
+		devParams = append(devParams, fmt.Sprintf("iothread=%s", scsiCon.IOThread))
+	}
 
 	qemuParams = append(qemuParams, "-device")
 	qemuParams = append(qemuParams, strings.Join(devParams, ","))
diff --git a/qemu/qemu_test.go b/qemu/qemu_test.go
index 1c63e42bdb..0506f4240f 100644
--- a/qemu/qemu_test.go
+++ b/qemu/qemu_test.go
@@ -350,7 +350,7 @@ func TestVSOCKValid(t *testing.T) {
 }
 
 var deviceSCSIControllerStr = "-device virtio-scsi-pci,id=foo"
-var deviceSCSIControllerBusAddrStr = "-device virtio-scsi-pci,id=foo,bus=pci.0,addr=00:04.0,disable-modern=true"
+var deviceSCSIControllerBusAddrStr = "-device virtio-scsi-pci,id=foo,bus=pci.0,addr=00:04.0,disable-modern=true,iothread=iothread1"
 
 func TestAppendDeviceSCSIController(t *testing.T) {
 	scsiCon := SCSIController{
@@ -361,6 +361,7 @@ func TestAppendDeviceSCSIController(t *testing.T) {
 	scsiCon.Bus = "pci.0"
 	scsiCon.Addr = "00:04.0"
 	scsiCon.DisableModern = true
+	scsiCon.IOThread = "iothread1"
 	testAppend(scsiCon, deviceSCSIControllerBusAddrStr, t)
 }