There is a problem with Asterisk server showing high Load Average I can not explain.
Ny setup is:
- Asterisk 13.1.0
- Linux 3.13.0-24 (Ubuntu Server)
- Dual socket (Xeon E5-2620) server, HT enabled – 24 cores total; 32G RAM
Asterisk is used for sending voice messages. I have one upstream SIP provider, no hardware telephony cards. There are only alaw/ulaw allowed in sip.conf.
I use AMI Originate command for starting a call; then I execute Playback() in context for sending pre-recorded voice message (ulaw files in local ext4 FS). There is no other interaction with callee, no IVR menu, no call recording. A couple very simple Perl AGI scripts save call result to DBs (MySQL and MSSQL (via Perl Sybase)); usually there are 1-2 AGI calls per Originate. Also, there is almost no processing in extension – literally 20 lines of pre-setting veriables for CDR() and a couple AGI calls. There is only one AMI connection I use for initiating all calls.
The specific is – most calls are not answered. I initiate up to 50 calls per second, but only 5-10 are actualy picked up and listened.
The problem is – I have very low CPU % usage, but very high LA.
If I itintiate 20-25 cps – 20-24 LA, but if I try to increase it up to 50cps, the LA climbs up to 90+. After ~50LA, there are problems with audio quality (and I can understand why).
Most Asterisk users claim they have way more call volume with less powerful hardware.
# uptime
12:56:36 up 9 days, 15:52, 1 user, load average: 32,10, 33,45, 33,10
#vmstat -w 1
procs ---------------memory-------------- ---swap-- -----io---- -system-- ------cpu-----
r b swpd free buff cache si so bi bo in cs us sy id wa st
3 0 0 30322760 199176 832452 0 0 0 0 237471 38738 5 8 87 0 0
3 0 0 30319148 199176 832500 0 0 0 0 188340 38960 4 6 90 0 0
3 0 0 30325528 199176 832564 0 0 0 26 319903 43916 6 10 83 0 0
105 0 0 30270288 199176 832568 0 0 0 14 175216 39014 4 6 90 0 0
16 0 0 30307908 199176 832572 0 0 0 0 323598 43428 11 12 77 0 0
# mpstat 1
Linux 3.13.0-24-generic (asterisk2) 25.02.2015 _x86_64_ (24 CPU)
13:18:09 CPU %usr %nice %sys %iowait %irq %soft %steal %guest %gnice %idle
13:18:10 all 5,77 0,00 7,90 0,00 0,17 0,00 0,00 0,00 0,00 86,16
13:18:11 all 5,56 0,00 8,83 0,00 0,21 0,00 0,00 0,00 0,00 85,40
13:18:12 all 10,29 0,00 11,42 0,00 0,25 0,00 0,00 0,00 0,00 78,03
13:18:13 all 9,70 0,00 10,75 0,00 0,21 0,00 0,00 0,00 0,00 79,34
# uname -a
Linux asterisk2 3.13.0-24-generic #46-Ubuntu SMP Thu Apr 10 19:11:08 UTC 2014 x86_64 x86_64 x86_64 GNU/Linux
# cat /proc/cpuinfo
processor : 0
vendor_id : GenuineIntel
cpu family : 6
model : 45
model name : Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz
stepping : 7
microcode : 0x70d
cpu MHz : 2000.216
cache size : 15360 KB
physical id : 0
siblings : 12
core id : 0
cpu cores : 6
apicid : 0
initial apicid : 0
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips : 4000.43
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
...
processor : 23
vendor_id : GenuineIntel
cpu family : 6
model : 45
model name : Intel(R) Xeon(R) CPU E5-2620 0 @ 2.00GHz
stepping : 7
microcode : 0x70d
cpu MHz : 2000.216
cache size : 15360 KB
physical id : 1
siblings : 12
core id : 5
cpu cores : 6
apicid : 43
initial apicid : 43
fpu : yes
fpu_exception : yes
cpuid level : 13
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe syscall nx pdpe1gb rdtscp lm constant_tsc arch_perfmon pebs bts rep_good nopl xtopology nonstop_tsc aperfmperf eagerfpu pni pclmulqdq dtes64 monitor ds_cpl vmx smx est tm2 ssse3 cx16 xtpr pdcm pcid dca sse4_1 sse4_2 x2apic popcnt tsc_deadline_timer aes xsave avx lahf_lm arat epb xsaveopt pln pts dtherm tpr_shadow vnmi flexpriority ept vpid
bogomips : 4001.85
clflush size : 64
cache_alignment : 64
address sizes : 46 bits physical, 48 bits virtual
# cat /proc/interrupts
CPU02 CPU23
0: 24 0 IR-IO-APIC-edge timer
8: 1 0 IR-IO-APIC-edge rtc0
9: 2 0 IR-IO-APIC-fasteoi acpi
16: 33 0 IR-IO-APIC-fasteoi ehci_hcd:usb1
23: 107 0 IR-IO-APIC-fasteoi ehci_hcd:usb2
88: 0 0 DMAR_MSI-edge dmar0
89: 0 0 DMAR_MSI-edge dmar1
90: 1855369 0 IR-PCI-MSI-edge ahci
91: 1 0 IR-PCI-MSI-edge eth0
92: 11296 0 IR-PCI-MSI-edge eth0-TxRx-0
93: 790 0 IR-PCI-MSI-edge eth0-TxRx-1
94: 85066770 0 IR-PCI-MSI-edge eth0-TxRx-2
95: 6851 0 IR-PCI-MSI-edge eth0-TxRx-3
96: 174614 0 IR-PCI-MSI-edge eth0-TxRx-4
97: 4846139 0 IR-PCI-MSI-edge eth0-TxRx-5
98: 136593 0 IR-PCI-MSI-edge eth0-TxRx-6
99: 1294090 0 IR-PCI-MSI-edge eth0-TxRx-7
109: 2 0 IR-PCI-MSI-edge ioat-msix
110: 2 0 IR-PCI-MSI-edge ioat-msix
111: 2 0 IR-PCI-MSI-edge ioat-msix
112: 2 0 IR-PCI-MSI-edge ioat-msix
113: 2 0 IR-PCI-MSI-edge ioat-msix
114: 2 0 IR-PCI-MSI-edge ioat-msix
115: 2 0 IR-PCI-MSI-edge ioat-msix
116: 2 0 IR-PCI-MSI-edge ioat-msix
117: 0 0 IR-PCI-MSI-edge ioat-msix
118: 0 0 IR-PCI-MSI-edge ioat-msix
119: 0 0 IR-PCI-MSI-edge ioat-msix
120: 0 0 IR-PCI-MSI-edge ioat-msix
121: 0 0 IR-PCI-MSI-edge ioat-msix
122: 0 0 IR-PCI-MSI-edge ioat-msix
123: 0 0 IR-PCI-MSI-edge ioat-msix
124: 0 0 IR-PCI-MSI-edge ioat-msix
NMI: 3642 1990 Non-maskable interrupts
LOC: 53207172 19108700 Local timer interrupts
SPU: 0 0 Spurious interrupts
PMI: 3642 1990 Performance monitoring interrupts
IWI: 804483 60489 IRQ work interrupts
RTR: 0 0 APIC ICR read retries
RES: 60096784 31495629 Rescheduling interrupts
CAL: 4046461325 4101338127 Function call interrupts
TLB: 2390847639 1479027286 TLB shootdowns
TRM: 0 0 Thermal event interrupts
THR: 0 0 Threshold APIC interrupts
MCE: 0 0 Machine check exceptions
MCP: 2501 2501 Machine check polls
ERR: 0
MIS: 0
# atop
CPL | avg1 22.45 | avg5 22.65 | | avg15 22.74 | | csw 379728 | intr 1612164 | | | numcpu 24 |
MEM | tot 31.4G | free 28.4G | cache 829.3M | dirty 0.0M | buff 194.7M | slab 188.0M | | | | |
SWP | tot 32.0G | free 32.0G | | | | | | | vmcom 737.1M | vmlim 47.7G |
MDD | md0 | busy 0% | read 0 | write 12 | KiB/r 0 | KiB/w 4 | MBr/s 0.00 | MBw/s 0.01 | avq 0.00 | avio 0.00 ms |
DSK | sda | busy 1% | read 0 | write 11 | KiB/r 0 | KiB/w 5 | MBr/s 0.00 | MBw/s 0.01 | avq 1.00 | avio 12.7 ms |
DSK | sdb | busy 1% | read 0 | write 11 | KiB/r 0 | KiB/w 5 | MBr/s 0.00 | MBw/s 0.01 | avq 1.00 | avio 11.6 ms |
NET | transport | tcpi 1994 | tcpo 2452 | udpi 17159 | udpo 14811 | tcpao 117 | tcppo 1 | tcprs 0 | tcpie 0 | udpip 0 |
NET | network | ipi 19235 | ipo 17268 | ipfrw 0 | deliv 19235 | | | | icmpi 7 | icmpo 0 |
NET | eth0 0% | pcki 19345 | pcko 17272 | si 3256 Kbps | so 2954 Kbps | coll 0 | erri 0 | erro 0 | drpi 0 | drpo 0 |
You can see, there are very high numbers in cs and in vmstat fields. I can not explain them.
So, as far as I get it – there are bursts of threads becoming executable in a very short time (you can see one such burst in vmstat output). But what in my setup can cause such thing?
I tried:
- Playing with codec packetization in sip.conf (there was an idea that I have too much micro-packets being sent);
- Changing playback file format;
- Disabling AGI script calls completely (by commenting them out in extensions.conf);
- Changing the way I use AMI channel (changing intervals and burst amounts to flatten load)
but nothing helped.
I checked everything I can think of – there is no disk IO, no other apps on this server.
There are guys in mailllist with similar problem, but that was not resolved, and it was quite a long ago.
One more thought – I have one more server with same problem with very similar hardware and Asterisk config, but there Asterisk 1.8 (FreePBX) and CentOS are being used. I suspect, this leads to my particular usage.
Maybe, this is core problem with AMI and I should use something else for mass-initialing calls?
EDIT1:
Here is my LA graph:
EDIT2: Here is Asterisk strace. Its relatively the same on high an low load. I am not a linux programmer myself, can't interpret it properly.
# strace -f -q -c -p 17150
^C% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
42.05 1595.370429 13209 120778 18231 futex
41.21 1563.521630 6304523 248 14 restart_syscall
15.96 605.470340 4726 128105 26 poll
0.23 8.811410 12037 732 nanosleep
0.16 5.903679 26 228693 22073 read
0.15 5.600020 66 85202 write
Best Answer
Ookay, I figured it out. This is just workaround, but the problem has dropped to acceptable level for me.
After un-wanted reboot in a middle of a day I noticed that Load Average dropped greatly! I checked our server monitoring system - LA always climbed up little-by-little in a 3-4 hours of continuous (and stable) load. This was un-noticable, because I was not able to reboot it during day before.
As I said, I have a couple Perl scripts, that are called via
AGI()application. One of them is called inhextension; it just runs one simple DB query. It turned out that sometimes DB become overloaded a bit; queries have to wait for 200-500ms; Asterisk has to wait until Perl script finishes.So, I thied to
fork()my Perl script at start - making AGI() call return always immediately. This helped a lot! LA became much stable. This is not a complete solution - it seems something it still corrupting in Asterisk' insides, but much slower, this is almost not a problem.For those seeking ready-for-use piece of code (dont forget to get all variables before
fork()ing, as you will not be able to access$AGIafter):It seems like a bug - but I wonder why there is no people with such problem others than me.
EDIT1: Well, the problem gone completely after eliminating
AGIcalls. I simply made a couple customODBCfunctions (func_odbc.conf), that just save information for asynchronous processing (it processed later by separate perl daemon). LA dropped from 20-25 down to 0.5-0.9 (!). I never thoughtAGIcan cause such huge load.