Description

Client upgraded an EX4300 VC (4 members) from 14.1x53 to 21.4r3-s6. After upgrade, the utilization on the "master" FPC is running close to 100% utilization. Prior to the upgrade, utilization was typically 30-40%. It's been about a week since the upgrade and this utilization issue continues. The client is also noticing some performance issues in their network since the upgrade. Looking for assistance in troubleshooting what's causing this utilization problem. RSI and Log files are attached to the case.

Solution

The pfex_junos process consumes the mayor portion of the CPU:

 

 PID USERNAME PRI NICE  SIZE  RES STATE  TIME  WCPU COMMAND
 10   root    155  52   0K  16K RUN  306:33 27.39% idle
 1627 root   -52 -52  642M  235M umtx  346:42 18.65% pfex_junos
 1627 root    68  0  642M  235M RUN  346:42 12.30% pfex_junos
 1824 root    47  0 16792K 8620K select 29:19 2.69% ksyncd
 1621 root    48  0 67952K 28764K select 12:49 1.22% chassisd
 65   root    -8  0   0K  16K mdwait  0:15 1.03% md0

 

  • Some SFP being used in the uplink module for different members of the Virtual chassis:

 

Line 111:   Xcvr 1    REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR
Line 112:   Xcvr 2    REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR
Line 113:   Xcvr 3    REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR
Line 115:   Xcvr 5    REV 01  740-021309  XXXXXXXXXXX    SFP+-10G-LR
Line 116:   Xcvr 6    REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR
Line 117:   Xcvr 7    REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR
Line 126:   Xcvr 32            NON-JNPR   XXXXXXXXXXX    SFP+-10G-LR
Line 128:   Xcvr 34   REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR
Line 133:   Xcvr 0    REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR
Line 134:   Xcvr 1    REV 01  740-021309  XXXXXXXXXXX    SFP+-10G-LR
Line 135:   Xcvr 2    REV 01  740-021309  XXXXXXXXXXX    SFP+-10G-LR
Line 136:   Xcvr 4    REV 01  740-021309  XXXXXXXXXXX    SFP+-10G-LR
Line 137:   Xcvr 5    REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR
Line 138:   Xcvr 6    REV 01  740-021309  XXXXXXXXXXX    SFP+-10G-LR
Line 139:   Xcvr 7    REV 01  740-031981  XXXXXXXXXXX    SFP+-10G-LR

 

The above will be expected as per design; This is a product limitation, because software linkscan is enabled by default, which causes the CPU utilization to go up. There is no way to disable it.

 

Reference: CPU usage of pfex_junos process increases when adding SFP to uplink module of EX4300-32F

 

Important: We also found an internal PR reported for high CPU for Pfex_junos process after upgrading to 21.4R3 in the EX4300 Virtual Chassis.  After checking the internal and confidential PR, I found that the Planned-Release{1}-Changed-From-To: 21.4R3-S7-X1->21.4R3-S8-X1.

 

We kindly request you to wait for the 21.4R3-S8.5 junos code available in the below Juniper public portal Download Results for EX4300

Modification History

2024-04-02 : Article Created