Deeper look at CPU utilization : SLOB example

This is a followup to my previous posts on Deeper look at CPU utilization :

• Deeper look at CPU utilization : The power of PMU events
• Deeper look at CPU utilization : TMAM Example

Following a comment from Kevin Closson here is the hierarchical execution cycles breakdown based on the TMAM method before and after enabling HUGEPAGES when running SLOB for testing Logical I/O.

Try these experiments with cached SLOB. That'll be an eye opener. https://t.co/j5l7EljdR2

— Kevin (@kevinclosson) October 27, 2017

This will let’s us identify our micro-architectural bottlenecks and correctly characterize the SLOB workloads !I will be using the same system configuration as in my previous posts.

Here is an extract form the SLOB conf :

• WORK_UNIT : 256
• SCALE : 500M
• RUN_TIME : 180
• UPDATE_PCT:0
• SCAN_PCT:0

Without HUGEPAGES :

Hierarchical execution cycles breakdown :

With HUGEPAGES :

Hierarchical execution cycles breakdown :

 

As in the previous example enabling HUGEPAGE has significantly reduced the pressure on DTLB ! As a result we can see that there is a slight improvement in our CPI and  LIO rate.

Workload Characterization :

EXTRAT :

Here is the memory bandwidth consumed in the second case :

That’s it 😀