From a24478aad22689c1a3a19cb7c6cfda60a9b108bc Mon Sep 17 00:00:00 2001 From: Branislav Jansik <branislav.jansik@vsb.cz> Date: Tue, 31 Jan 2023 16:55:08 +0100 Subject: [PATCH] Update energy.md --- docs.it4i/general/energy.md | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/docs.it4i/general/energy.md b/docs.it4i/general/energy.md index 2cdf5b59f..af02f2a0d 100644 --- a/docs.it4i/general/energy.md +++ b/docs.it4i/general/energy.md @@ -18,10 +18,19 @@ Core frequency capping is implemented for the Karolina supercomputer: ### Performance Impact -The performance impact depends strongly on the [arithmetic intensity][1][2] of the job. +The performance impact depends on the [arithmetic intensity][1] of the job. +The [arithmetic intensity][2] is a measure of floating-point operations (FLOPs) performed by a given code (or code section) relative to the amount of memory accesses (Bytes) that are required to support those operations. It is defined as a FLOP per Byte ratio (F/B). It is a characteristics of the particular computational algorithm. + +In general, the processor frequency capping has low performance impact for computation with intensity below +the [ridge point][2], such as memory bound computations. For intensive, CPU bound computations, the impact is directly +proportional to the frequency reduction. + +On Karolina, relative time increase factor up to 1.3 is observed for intensive workloads on CPU, up to 1.1 on GPU. No slowdown is observed for memory bound workloads. ### Energy Saved +The enegy efficiency in floating point operations per joule is increased by about 30% for CPU workloads, about 25% for GPU workloads. + ## Barbora None implemented yet. @@ -34,5 +43,5 @@ None implemented yet. None implemented yet. -[1]: https://people.eecs.berkeley.edu/~kubitron/cs252/handouts/papers/RooflineVyNoYellow.pdf -[2]: https://en.wikipedia.org/wiki/Roofline_model +[1]: https://en.wikipedia.org/wiki/Roofline_model +[2]: https://people.eecs.berkeley.edu/~kubitron/cs252/handouts/papers/RooflineVyNoYellow.pdf -- GitLab