Deeper look at CPU utilization : SLOB example

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

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.

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

Capture du 2017-10-30 16_09_56

Without HUGEPAGES :

Capture du 2017-10-30 18_17_20

Hierarchical execution cycles breakdown :

Capture du 2017-10-30 18_19_53

With HUGEPAGES :

Capture du 2017-10-30 18_45_54

Hierarchical execution cycles breakdown :

Capture du 2017-10-30 18_48_29

 

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 :

Capture

EXTRAT :

Here is the memory bandwidth consumed in the second case :

Capture 03

That’s it 😀

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