Stella Integrated scheduler

• GoS: Guarantee of CPU utilization and SSD block I/O SLA
• ANCS: Guarantee of network I/O SLA

PREREQUISITE

Because GoS and ANCS are designed for virtualized environment equipped with SSDs, it requires following environments.

• Modified Linux kernel 4.4.1
• KVM installed Linux
• SSD equipped virtual machines
• vhost-net enabled virtual machines

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GoS: Guarantee of CPU utilization and SSD block I/O SLA

GoS framework is a scheduling architecture between CPU and SSD block I/O for providing required performance to virtual machines running concurrently on a virtualized server. GoS includes different types of resource scheduler in a physical server, CPU and block I/O, to support diverse workload running on virtual machines with different characteristics (CPU-intensive or I/O-intensive).

SCHEDULING POLICIES

This module allocates CPU utilization and block I/O bandwidth of virtual machines and guarantees sla values (CPU utilization, block I/O bandwidth) for virtual machines. You can set sla options and sla value to each virtual machine via test.sh script file.

MODULE INSTALL GUIDE

GoS is loadable kernel model independent of kernel version. GoS can be installed both manually and automatically through scripts.

AUTOMATIC INSTALL

sudo ./set.sh

MANUAL INSTALL

1. make in the GoS directory

make

2. install drivers

insmod gos_start.ko
insmod cpu_stat.ko
insmod disk_stat.ko
insmod gos.ko

3. configure block I/O scheduler

echo noop > /sys/block/sdc/queue/scheduler
rmmod oios-iosched
insmod oios-iosched.ko && echo oios > /sys/block/sdc/queue/scheduler
echo 1 > /sys/block/sdc/queue/nomerges

HOW TO USE

Code setting

For the experiment, source should be modified.

1. Block allocation

   Modify unsigned long partition variable in oios-iosched.c file the array consists of {start block number, end block number}

2. Priority(performance) ratio of OIOS

   Modify static int prior[] variable in oios-iosched.c file It only supports 5 VMs

3. Number of vcpus

   Modify #define VCPU_NUM N macro in gos.h file The VCPU_NUM is the number of cores in the CPUs

4. Number of VMs

   Modify #define VM_UM N macro in gos.h file The VM_NUM is the number of VMs which have SLA setting in test.sh script file

Script setting

To run virtual machines with performance requirements and evaluate their performance using any CPU or bock I/O benchmark.

First, edit your performance requirements fields (sla_option, sla_vlaue) in test.sh shell script to generate virtual machines with performance requirements (SLA).

• sla_optaion: b_bw-require I/O bandwidth (B), c_usage-require CPU utilization (%, 1 core = 100%)
• sal_value: bandwidth in B or CPU utilization

for example, if you want to guarantee SSD I/O bandwidth of vm 1 to 100MB and CPU utilization of vm 2 to 200% (2 cores), you hava to set sla_option, sla_value of vm1 as b_bw, 100000 and c_usage, 200 for sla_option and sla_valule of vm 2

test.sh

#!/bin/bash

./insert_target_vm.sh vm1 b_bw 100000
./insert_target_vm.sh vm2 c_usage 200

Second, apply your performance requirements to GoS

./test.sh

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ANCS: Guarantee of network I/O SLA

ANCS is a loadable kernel module which dynamically allocates network bandwidth to virtual machines. Our goal is to guarantee QoS requirement of virtual machines through dynamic allocation of network resources in a virtualized server. We used scheduling method proposed in the paper ANCS*.

*ANCS: Achieving QoS through Dynamic Allocation of Network Resources in Virtualized Clouds

SCHEDULING POLICIES

This module allocates network bandwidth of virtual machines dynamically and propotionally to weight.

• Bandwidth of each virtual machine is set to "(weight / total weight) * (bandwidth capacity)".
• Ex) If we have running virtual machines A,B,C with weight 1,2,2, then each virtual machine uses 20%, 40%, 40% of maximum bandwidth capacity.

You can set the specific network performance of virtual machines.

• If you give a specific value of the performance in "max_credit" using proc file system, then upper limit of the network performance is configured.
• Setting lower limit can be done by changing "min_credit" as above.

This module supports work-conserving.

• If there's virtual machine not fully using it's bandwidth, then remaining bandwidth is reallocated to other virtual machine's so that utilization of network resources can be maximized.

MODULE INSTALL GUIDE

install scheduling module

• "vif" folder has a module source code, header file, Makefile.
• change current directory to "vif" folder and compile a module using "make".
• Before typing insmod vif.ko, you have to start virtual machines because this module requires vhost_net module.
• When compilation is done, you would get a loadable kernel module "vif.ko". insmod vif.ko

HOW TO USE

Run or start virtual machine after adding a module

• must install a module first because virtual machines which are executed before a module installation are not affected by a module

Use proc file system to set weight, min, max bandwidth of each virtual machine if needed

• weight is set to 1 by default
• min, max credit is set to 0 by default, meaning it has no upper, under limitaion of bandwidth.

Printing attributes of each virtual machine.

• A command that prints weight of second virtual machine. vif stands for virtual interface. cat /proc/ancs/vif2/weight

• A command that prints a maximum performance of first virtual machine in a form of bandwidth or packet per second (pps). cat /proc/oslab/vif1/max_credit

• A command that prints a minimum performance of first virtual machine. cat /proc/oslab/vif1/min_credit

Setting attributes of each virtual machine

• A command that sets a weight of first virtual machine "2". A bigger weight means a bigger priority. echo 2 > /proc/oslab/vif1/weight