Variation Among Processors Under Turbo-‐Boost

Variation Among Processors Under Turbo-Boost

Bilge Acun, Ph.D. Candidate Department of Computer Science University of Illinois at Urbana-Champaign

This talk is based on the publicaon: Bilge Acun, Phil Miller, Laxmikant Kale. ICS 2016. 1 “Variaon Among Processors under Turbo Boost in HPC Systems”. Motivation: Performance Variation

16% Performance Only 1% Variaon on Variaon on Edison, Blue Waters! Cab, Stampede! ��

�� Acun, Miller, Kale. “Variaon Among Processors under Turbo

�� Boost in HPC Systems” [ICS 2016]

�� 2 �� • 16K cores running local DGEMM kernel of Intel-MKL What is Dynamic Overclocking?

• Processor changes the frequency opportuniscally since it cannot run at the highest limit all the me. • E.g. Intel Turbo Boost Technology • Factors eﬀecng the dynamic frequency: • Type of the workload • Number of acve cores • Current consumpon �� • Power consumpon �� • Temperature Acun, Miller, Kale. “Variaon Among Processors under Turbo Boost in HPC Systems” [ICS 2016] ��

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�� Motivation: Frequency Variation

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�� Acun, Miller, Kale. “Variaon Among Processors under Turbo �� Boost in HPC Systems” [ICS 2016] �� 4

Edison: Intel Ivy Bridge Stampede, Cab: Intel Sandy Bridge Motivation: Frequency Variation

• Distribuon of steady-state frequencies on Edison Acun, Miller, Kale. “Variaon Among Processors under Turbo Boost in HPC Systems” [ICS 2016]

5 Why there is variation?

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�� Acun, Miller, Kale. “Variaon �� Among Processors under Turbo �� Boost in HPC Systems” [ICS 2016] � �� 6 �� Is it caused by temperature?

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�� Acun, Miller, Kale. “Variaon Among Processors under Turbo

�� Boost in HPC Systems” [ICS 2016] �� 7 �� Is it caused by temperature?

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�� Acun, Miller, Kale. “Variaon Among Processors under Turbo

�� Boost in HPC Systems” [ICS 2016] ��

�� 8 Is it caused by power? Acun, Miller, Kale. “Variaon Among Processors under Turbo { Fast processors’ power are Boost in HPC Systems” [ICS 2016] similar to uniform Slow and variable processors distribuon have higher power 9 What can we do about it?

1. Disable Turbo-Boost 2. Replacing the slow chips 3. Selecvely idling the cores 4. Dynamic load balancing Acun, Miller, Kale. “Variaon Among Processors under Turbo Boost in HPC Systems” [ICS 2016]

10 Solution 1: Disable Turbo-Boost? Acun, Miller, Kale. “Variaon Among Processors under Turbo Boost in HPC Systems” [ICS 2016] u Naïve-DGEMM slows down more compared to MKL because it was running at higher frequency with Turbo Boost. 11 u Jacobi2D suﬀers less from disabling Turbo-Boost because it’s memory intensive. Solution 2: Replace the chips?

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�� Acun, Miller, Kale. “Variaon Among Processors under Turbo

�� Boost in HPC Systems” [ICS 2016] �� 12 Solution 3: Idling the cores?

�� Acun, Miller, Kale. “Variaon

�� Among Processors under Turbo Boost in HPC Systems” [ICS 2016]

�� 13 �� Solution 4: Speed-Aware Load Balancing!

• Runme tracks processor speeds dynamically +LBTestPESpeed • Balance the workload with taking into account the speed

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�� Acun, Miller, Kale. “Variaon

�� Among Processors under Turbo Boost in HPC Systems” [ICS 2016] �� 14 �� Summary & Conclusion

Soware can do a lot more if the desired support and access is given. Acun, Miller, Kale. “Variaon Among Processors under Turbo Boost in HPC Systems” [ICS 2016]

15 Future Work

• Variaon analysis on newer generaon processors • Variaon in memory operaons Acun, Miller, Kale. “Variaon Among Processors under Turbo Boost in HPC Systems” [ICS 2016]