156-315.81.20 Performance Tuning (SecureXL/CoreXL) Practice Question
Exhibit
Kernel: 80% SecureXL: 10% User Space: 5%
Refer to the exhibit. An administrator sees this CPU distribution on a gateway. What is the most appropriate action?
⚠ Common exam trap
Candidates often assume the issue is a hardware failure or a need for more RAM, rather than recognizing that non-acceleratable features are forcing traffic into the slower kernel path.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
Review security policy for non-acceleratable features
This CPU breakdown shows high kernel utilization, suggesting the firewall engine is overburdened, while SecureXL is underutilized. This indicates that traffic is not being successfully offloaded. The administrator should investigate policies or features preventing acceleration, such as complex rules or inspection settings. Addressing this allows the gateway to shift the load from the kernel to the faster SecureXL path, significantly improving throughput and responsiveness.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✗
Increase the number of CoreXL instances
Why it's wrong here
Increasing instances would only split the same high-load kernel tasks across more cores. If the traffic itself is not eligible for SecureXL offloading, adding more instances will not address the root cause, which is that the packets are being processed by the slower, resource-intensive kernel path instead of accelerated.
- ✓
Review security policy for non-acceleratable features
Why this is correct
High kernel usage paired with low SecureXL usage indicates that traffic is failing to hit the fastpath. Reviewing policies for features that bypass acceleration—such as certain NAT configurations, advanced inspection, or logging requirements—is the correct step to identify why traffic is not being offloaded appropriately.
- ✗
Lower the MTU size on the interfaces
Why it's wrong here
MTU settings affect packet fragmentation and connectivity, not the CPU distribution between the kernel and the acceleration layer. Adjusting MTU is a network connectivity troubleshooting step, not a performance tuning action to resolve CPU imbalances or improper usage of the SecureXL acceleration path for packet processing.
- ✗
Reinstall the gateway software
Why it's wrong here
A full reinstallation is unnecessary and disruptive. The CPU distribution issue is a configuration or traffic pattern symptom that can be resolved through policy tuning and optimization of the existing setup. Reinstalling does not address the underlying reason why the system is failing to offload the traffic effectively.
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JA
Written and reviewed by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
Last reviewed September 2026 · checked against the official Check Point exam blueprint
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