[Asterisk-Users] Load spikes with 1.0.10

[Gavin Hamill]

Hi, I have a trivial setup on a 2.4GHz Xeon Dell PE 1750 SCSI machine 
dealing with 4 ports of E1 in an 'inline PBX' arrangement.

My extensions.conf is simply:

[general]
static=yes
writeprotect=yes

[frompstn]
exten => _31.,1,Dial(Zap/g2/${EXTEN})
exten => _31.,2,Congestion

[fromaxxess]
exten => _13.,1,Dial(SIP/${EXTEN},,h)
exten => _13.,2,Congestion
exten => _31.,1,Dial(Zap/g2/${EXTEN})
exten => _31.,2,Congestion
include => outbound

[outbound]
exten => _X.,1,Dial(Zap/g1/${EXTEN})
exten => _X.,2,Congestion

We have a full 30-channel PRI and a 4-channel partial PRI and are 
experiencing load spikes that I can't find the source of.

The machine Debian sarge on the default 2.6.8-2-686 kernel, and no other 
daemons are running than sshd.

The machine is doing no IP work - purely TDM, yet on a Xeon 2.4GHz 
machine, the load average is sitting at 0.6 with 40 active Zap channels 
(i.e. 20 live calls) and will randomly jump to 2 (with call quality 
starting to stutter)

A few seconds of vmstat:


procs -----------memory---------- ---swap-- -----io---- --system-- 
----cpu----
 r  b   swpd   free   buff  cache   si   so    bi    bo   in    cs us sy 
id wa
 7  0      0 223560   1276 223040    0    0     3    10   83    94  1  2 
97  0
 0  0      0 223552   1284 223040    0    0     0    16 5128  3461  1  0 
98  1
 0  0      0 223552   1284 223040    0    0     0     0 5094  3319 10  9 
81  0
 0  0      0 223552   1284 223040    0    0     0    16 5130  2955  1 10 
89  0
 0  0      0 223552   1292 223040    0    0     0    60 5121  2918  0  1 
97  2
 0  0      0 223552   1292 223040    0    0     0     0 5031  2936  1  0 
99  0

Does this sound about normal for what is just shuffling data between 
ports of the Sangoma A104? I want to record the call data with the 
'Monitor' application but this just causes the load to increase even 
more (even though 'hdparm' shows 70MB/sec disk transfer with low 
user+system CPU usage)

 /proc/interrupts is
            CPU0
  0:  423253622    IO-APIC-edge  timer
  1:        175    IO-APIC-edge  i8042
  9:          0   IO-APIC-level  acpi
 11:          0   IO-APIC-level  ohci_hcd
 12:         58    IO-APIC-edge  i8042
 15:         13    IO-APIC-edge  ide1
177:     533330   IO-APIC-level  ioc0
185:         29   IO-APIC-level  ioc1
193: 1311243931   IO-APIC-level  wanpipe1, wanpipe2, wanpipe3, wanpipe4
201:   13289965   IO-APIC-level  eth0
217:    5420038   IO-APIC-level  eth2
NMI:          0
LOC:  423311408
ERR:          0
MIS:          0

Help! :)

Cheers,
Gavin.