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Initial Public Release
Cisco IOS® XE Denali 16.2
Cisco IOS XE 3.x - All versions of Cisco IOS XE 3.x
The show command on Cisco IOS XE based products might not report true platform memory usage.
On products that run Cisco IOS XE (see the Products Affected section), the Linux kernel uses free memory space in order to expand its cache. This results in the free memory space to decrease over time and might appear as if the router experiences a memory leak. This could be a false alarm since the cache can be freed if memory is needed.
When you use the command show platform software status control-processor, over time the free memory might display a smaller percentage as shown in this example highlighted in bold.
Slot Status Total Used (Pct) Free (Pct) Committed (Pct)
RP0 Healthy 3972008 3942316 (99%) 29692 ( 1%) 2392632 (60%)
There is one solution and two workarounds.
The solution is to upgrade to Cisco IOS XE Denali 16.3.
In order to obtain a good estimate of free memory, enter the command monitor platform software process rp active:
top - 17:02:19 up 26 days, 22:52, 0 users, load average: 0.00, 0.00, 0.00
Tasks: 445 total, 1 running, 444 sleeping, 0 stopped, 0 zombie
Cpu(s): 0.8% us, 1.7% sy, 0.0% ni, 97.5% id, 0.0% wa, 0.0% hi, 0.0% si, 0.0% st
Mem: 3972008k total, 3946308k used, 25700k free, 223416k buffers
Swap: 0k total, 0k used, 0k free, 1537140k cached
In order to estimate the free memory, add free + buffers + cached memory. From the previous example, the estimated free memory is 25700k + 223416k + 1537140k = 1786256k. This indicates that the estimated free memory is 45% of the total memory.
This example lists the steps to be followed in order to get accurate used and free memory on an active Route Processor (RP).
Note: Use of the sync command might increase CPU utilization of the RP.
- Obtain a one day platform shell license. See Product License Registration. This requires a CCO account.
- Install the shell license obtained in Step 1.
- Enter the config command platform shell.
- Enter the exec command request platform software system shell rp active. This results in a platform shell prompt.
- At the platform shell prompt, enter y.
- At the shell prompt, enter sync;echo 3 > /proc/sys/vm/drop_caches.
- Exit the platform shell.
- Enter the command show platform software status control-processor.
This displays an accurate value for used and free memory using show platform software status control-processor and querying the SNMP MIB browser in order to decipher memory usage.
Free memory - 126.96.36.199.188.8.131.52.184.108.40.206.1.13
Used memory - 220.127.116.11.18.104.22.168.22.214.171.124.1.12
To follow the bug ID link below and see detailed bug information, you must be
a registered customer and you must be logged in.
|CSCuc40262 (registered customers only)
||Linux kernel cache is leading to confusion over memory usage
For More Information
If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:
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