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Cisco Bug: CSCua79562 - Disable SLD periodic data collection

Last Modified

Apr 17, 2020

Products (17)

  • Cisco ASR 9000 Series Aggregation Services Routers
  • Cisco CRS-1 Line Card Chassis (Dual)
  • Cisco CRS-1 16-Slot Line Card Chassis
  • Cisco CRS-1 Line Card Chassis (Multi)
  • Cisco IOS XR Software
  • Cisco CRS-1 4-Slot Single-Shelf System
  • Cisco ASR 9010 Router
  • Cisco CRS-1 8-Slot Line Card Chassis
  • Cisco XR 12410 Router
  • Cisco CRS-1 Fabric Card Chassis
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Known Affected Releases

4.1.2.BASE 4.2.3.BASE

Description (partial)


A node (RP or LC) may experience reload after observation of high
CPU usage over extended period of time. The reload generated a
kernel core. The core dump process also generates a text file
that indicates the node is reloaded by the process 'wdsysmon'
due to the monitor thread of that process has hung for too long.
The threshold of the wait time is 4 minutes, meaning if this thread
of wdsysmon is blocked for more than 4 minutes, the node will reload.


The issue is caused by the process 'sld' running at priority 9.
Most IOS-XR processes running at priority 10. Due to strict priority
scheduling in QNX, when there is an endless supply of priority 10
threads in READY state, priority 9 threads can be starved. In this
case, a router is observed to have 100% CPU utilization for 3 days,
and all 3 threads of the process 'sld' are starved. One of the threads
has made a QNX procfs call, that happens to block the monitor thread
of wdsysmon, which is also trying to lock the same procfs resource.
The wdsysmon process runs periodically to monitor conditions of 
critical system resources. The periodicity of its activity cannot
be changed. The 'sld' process thread 2 is also periodically running
(every 60 second) to collect some lightweight trace buffer and SHIP
counters. This behavior is on by default, without any config.

In summary, the key condition here is that priority 10 threads
are starving priority 9 threads such as 'sld'
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Bug Details Include

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