The document discusses Linux resource management techniques like ulimits, quotas, CPU affinity, and cGroups. It provides examples of configuring ulimits and CPU affinity at the process level using tools like ulimit, taskset, and proc files. It also explains how cGroups can be used to control resources like CPU, memory, block I/O for groups of processes in a hierarchy.

1. Linux Resource Linux Resource
ManagementManagement
Marian HackMan Marinov
Chief System Architect
mm@siteground.com

2. Who am I?Who am I?
●
Chief System Architect - SiteGroundChief System Architect - SiteGround
●
Linux System Administrator since 1996Linux System Administrator since 1996
●
Teaching LSA and NetSec at FMI SofiaTeaching LSA and NetSec at FMI Sofia
●
Organizing OpenFest and othersOrganizing OpenFest and others

3. ●
ulimitulimit
●
quotaquota
●
CPU affinity per-device and per-processCPU affinity per-device and per-process
●
cGroupscGroups

4. cpu time (seconds, -t) unlimitedcpu time (seconds, -t) unlimited
scheduling priority (-e) 0scheduling priority (-e) 0
real-time priority (-r) 0real-time priority (-r) 0
file size (blocks, -f) unlimitedfile size (blocks, -f) unlimited
pending signals (-i) 96832pending signals (-i) 96832
open files (-n) 1024open files (-n) 1024
file locks (-x) unlimitedfile locks (-x) unlimited
pipe size (512 bytes, -p) 8pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200POSIX message queues (bytes, -q) 819200
max user processes (-u) 200max user processes (-u) 200
max locked memory (kbytes, -l) 64max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimitedmax memory size (kbytes, -m) unlimited
virtual memory (kbytes, -v) unlimitedvirtual memory (kbytes, -v) unlimited
core file size (blocks, -c) 0core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimiteddata seg size (kbytes, -d) unlimited
stack size (kbytes, -s) 8192stack size (kbytes, -s) 8192
ulimitsulimits

5. app1
userXuserX
user procsuser procs
userX 1userX 1
tty:tty:
core file size (blocks, -c) 0core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimiteddata seg size (kbytes, -d) unlimited
scheduling priority (-e) 0scheduling priority (-e) 0
file size (blocks, -f) unlimitedfile size (blocks, -f) unlimited
pending signals (-i) 96832pending signals (-i) 96832
max locked memory (kbytes, -l) 64max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimitedmax memory size (kbytes, -m) unlimited
open files (-n) 1024open files (-n) 1024
pipe size (512 bytes, -p) 8pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0real-time priority (-r) 0
stack size (kbytes, -s) 8192stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimitedcpu time (seconds, -t) unlimited
max user processes (-u) 200max user processes (-u) 200
virtual memory (kbytes, -v) unlimitedvirtual memory (kbytes, -v) unlimited
file locks (-x) unlimitedfile locks (-x) unlimited
ulimitsulimits

6. app2
app1
userXuserX
userXuserX
user procsuser procs
userX 2userX 2
tty:tty:
core file size (blocks, -c) 0core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimiteddata seg size (kbytes, -d) unlimited
scheduling priority (-e) 0scheduling priority (-e) 0
file size (blocks, -f) unlimitedfile size (blocks, -f) unlimited
pending signals (-i) 96832pending signals (-i) 96832
max locked memory (kbytes, -l) 64max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimitedmax memory size (kbytes, -m) unlimited
open files (-n) 1024open files (-n) 1024
pipe size (512 bytes, -p) 8pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0real-time priority (-r) 0
stack size (kbytes, -s) 8192stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimitedcpu time (seconds, -t) unlimited
max user processes (-u) 200max user processes (-u) 200
virtual memory (kbytes, -v) unlimitedvirtual memory (kbytes, -v) unlimited
file locks (-x) unlimitedfile locks (-x) unlimited
ulimitsulimits

7. app2
app1
app3
userXuserX
userXuserX
userXuserX
user procsuser procs
userX 3userX 3
tty:tty:
core file size (blocks, -c) 0core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimiteddata seg size (kbytes, -d) unlimited
scheduling priority (-e) 0scheduling priority (-e) 0
file size (blocks, -f) unlimitedfile size (blocks, -f) unlimited
pending signals (-i) 96832pending signals (-i) 96832
max locked memory (kbytes, -l) 64max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimitedmax memory size (kbytes, -m) unlimited
open files (-n) 1024open files (-n) 1024
pipe size (512 bytes, -p) 8pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0real-time priority (-r) 0
stack size (kbytes, -s) 8192stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimitedcpu time (seconds, -t) unlimited
max user processes (-u) 200max user processes (-u) 200
virtual memory (kbytes, -v) unlimitedvirtual memory (kbytes, -v) unlimited
file locks (-x) unlimitedfile locks (-x) unlimited
ulimitsulimits

8. core file size (blocks, -c) 0core file size (blocks, -c) 0
data seg size (kbytes, -d) unlimiteddata seg size (kbytes, -d) unlimited
scheduling priority (-e) 0scheduling priority (-e) 0
file size (blocks, -f) unlimitedfile size (blocks, -f) unlimited
pending signals (-i) 96832pending signals (-i) 96832
max locked memory (kbytes, -l) 64max locked memory (kbytes, -l) 64
max memory size (kbytes, -m) unlimitedmax memory size (kbytes, -m) unlimited
open files (-n) 1024open files (-n) 1024
pipe size (512 bytes, -p) 8pipe size (512 bytes, -p) 8
POSIX message queues (bytes, -q) 819200POSIX message queues (bytes, -q) 819200
real-time priority (-r) 0real-time priority (-r) 0
stack size (kbytes, -s) 8192stack size (kbytes, -s) 8192
cpu time (seconds, -t) unlimitedcpu time (seconds, -t) unlimited
max user processes (-u) 200max user processes (-u) 200
virtual memory (kbytes, -v) unlimitedvirtual memory (kbytes, -v) unlimited
file locks (-x) unlimitedfile locks (-x) unlimited
app2
app1
app3
userXuserX
userXuserX
userXuserX
user procsuser procs
userX 4userX 4
app4
userXuserX
ssh:ssh:
tty:tty:
ulimitsulimits

9. ● login (on tty, via PAM)
● KDM, GDM, XDM & etc. (locally via PAM)
● ssh (remotely, via PAM and shell)
● pam_limits
– /etc/security/limits.conf
– /etc/security/limits.d/
● shell (sh, bash, zsh, csh, tcsh)
– /etc/profile.d/limits.[tcz]sh
ulimitsulimits how-tohow-to

10. $ cat /proc/self/limits
Limit Soft Limit Hard Limit Units
Max cpu time unlimited unlimited seconds
Max file size unlimited unlimited bytes
Max data size unlimited unlimited bytes
Max stack size 8388608 unlimited bytes
Max core file size 0 unlimited bytes
Max resident set unlimited unlimited bytes
Max processes 200 200 processes
Max open files 1024 4096 files
Max locked memory 65536 65536 bytes
Max address space unlimited unlimited bytes
Max file locks unlimited unlimited locks
Max pending signals 200 200 signals
Max msgqueue size 819200 819200 bytes
Max nice priority 0 0
Max realtime priority 0 0
Max realtime timeout unlimited unlimited us
ulimitsulimits how-tohow-to

11. $ cat /proc/self/limits
on older kernels:
$ echo -n "Max open files=2000:6000"
> /proc/self/limits
$ prlimit
ulimitsulimits how-tohow-to

12. Other kernel limits
● fs.file-max - max fd for the machine
● fs.nr_open - max fd per process
● fs.mount-max - max mounted filesystems
● kernel.threads-max

13. ● Dedicate a CPU to HW device
● Dedicate a CPU to a process
● taskset mask cmd
● /proc/interrupts
– /proc/irq/NUM/smp_affinity
– /proc/irq/NUM/smp_affinity_list
– /proc/irq/NUM/affinity_hint
CPU AffinityCPU Affinity

14. ● Dedicate a CPU to HW device
● Dedicate a CPU to a process
core0 core1
core2 core3
eth0 1Gbps
eth4 10Gbps
megaraid 6Gbps
CPU AffinityCPU Affinity

15. ● Dedicate a CPU to HW device
● Dedicate a CPU to a process
core0 core1
core2 core3
eth0 1Gbps
eth1 10Gbps
eth2 10Gbps
megaraid 6Gbps
core0 - eth1 10Gbps
core1 - eth2 10Gbps
core3 - megaraid 6Gbps
core4 - eth0 & processes
CPU AffinityCPU Affinity

16. taskset example
root@terion:~# taskset -p 2727
pid 2727's current affinity mask: ff
root@terion:~# taskset -pc 3 2727
pid 2727's current affinity list: 0-7
pid 2727's new affinity list: 3
root@terion:~# taskset -p 2727
pid 2727's current affinity mask: 8
root@terion:~# ps axf|grep 2727
2727 ? Ss 2:06 /usr/sbin/acpid
root@terion:~#

17. irq affinity example
root@terion:~# cat /proc/interrupts
CPU0 CPU1
16: 3567385 0 IO-APIC 16-fasteoi ehci_hcd:usb1
17: 4567 0 IO-APIC 17-fasteoi snd_hda_intel:
23: 50797 0 IO-APIC 23-fasteoi ehci_hcd:usb2
25: 78045696 0 PCI-MSI 512000-edge ahci
36: 12 0 PCI-MSI 409600-edge eth0
37: 169256226 0 PCI-MSI 1572864-edge iwlwifi
38: 3515939 0 PCI-MSI 524288-edge nvidia

18. irq affinity example
root@terion:~# cd /proc/irq/37
root@terion:/proc/irq/37# cat smp_affinity
ff
root@terion:/proc/irq/37# cat smp_affinity_list
0-7
root@terion:/proc/irq/37# echo 3 > smp_affinity_list
root@terion:/proc/irq/37# cat smp_affinity
08
root@terion:/proc/irq/37# cat smp_affinity_list
3
root@terion:/proc/irq/37#

19. Other resource limitations can be
enforced using virtualization
technologies like KVM, Xen, etc.

20. What if you want to set a limit to a
group of processes?

21. ● CPUSET
● CPU
● CPUACCT
● MEMORY
● BLKIO
● DEVICES
● freezer
● net_cls
● net_prio
● perf_event
● hudgetlb
cGroupscGroups

22. cGroupscGroups
● freezer
● net_cls
● net_prio
● perf_event
● hudgetlb
● CPUSET
● CPU
● CPUACCT
● MEMORY
● BLKIO
● DEVICES

23. ● cGroups have hierarchy
//
/user1/user1
/user2/user2
/user1/user3/user1/user3
cGroupscGroups

24. root@goblin:/cgroup# ls -1 cpuset*
cpuset.cpus
cpuset.mems
cpuset.cpu_exclusive
cpuset.mem_exclusive
cpuset.effective_cpus
cpuset.effective_mems
...
cGroupscGroups CPUSETCPUSET

25. root@goblin:/cgroup# ls -1 cpu.*
cpu.cfs_period_us
cpu.cfs_quota_us
cpu.rt_period_us
cpu.rt_runtime_us
cpu.shares
cpu.stat
cGroupscGroups CPUCPU

26. root@goblin:/cgroup# ls -1 cpuacct.*
cpuacct.stat
cpuacct.usage
cpuacct.usage_percpu
cpuacct.usage_all
cpuacct.usage_percpu_sys
cpuacct.usage_percpu_user
cpuacct.usage_sys
cpuacct.usage_user
CPUACCTCPUACCTcGroupscGroups

27. memory.memsw.failcnt
memory.memsw.limit_in_bytes
memory.memsw.max_usage_in_bytes
memory.memsw.usage_in_bytes
memory.limit_in_bytes memory.usage_in_bytes
memory.soft_limit_in_bytes
memory.max_usage_in_bytes
memory.move_charge_at_immigrate memory.failcnt
memory.numa_stat memory.stat
memory.oom_control memory.pressure_level
memory.swappiness memory.use_hierarchy
cGroupscGroups MEMORYMEMORY

28. blkio.throttle.io_service_bytes
blkio.throttle.io_serviced
blkio.throttle.read_bps_device
blkio.throttle.read_iops_device
blkio.throttle.write_bps_device
blkio.throttle.write_iops_device
cGroupscGroups BLKIOBLKIO

29. blkio.weight
blkio.weight_device
blkio.leaf_weight
blkio.leaf_weight_device
BLKIOBLKIOcGroupscGroups

30. cGroupscGroups
root@goblin:/cgroup# ls -1 devices.*
devices.allow
devices.deny
devices.list
DEVICESDEVICES

31. Marian HackMan Marinov
Chief System Architect
mm@siteground.com
QuestionsQuestions