Noteworthy-Reports.md

+# Why Warm-Up Messages Should Be Used
+
+Here is an example of why warm-up messages are important. This example show a UCP test on JUSUF. In it we see atrociously poor timings along the right half of the anti-diagonal. This is because these connections are tested first and only when the first message is sent are the UCP workers primed, as a result the first time the connection is tested the corresponding connection and worker need to be initialized. This effect averages out if more messages are averaged over or if the message size is larger. Effectively the right-side of the anti-diagonal shows the latency in finishing worker initialization and setting up connections.
+
+In the attached "Serial" report we see that this effect can also appears if connections are serially tested. We see though that the first tested connection between 0 and 63 is the slowest, this because the serially tested later anti-diagonal connections at that point are likely finished establishing their workers, their only remaining delay is establishing the connections to the relevant controllers.
+
+In the other attached report warm-up messages were included, in which case the effect vanishes. In it we can see the underlying structure of the full-fat--tree structure of the JUSUF interconnect.
+
+This demonstrates why using warm-up messages important. Using just 3 already helps improve results dramatically.
+
+[linktest_jusuf_ucp_64nx1c_512B_1Msg.pdf](https://gitlab.jsc.fz-juelich.de/cstao-public/linktest/uploads/6b6fd09e2a560ad1553637e8739bdc38/linktest_jusuf_ucp_64nx1c_512B_1Msg.pdf)
+
+[linktest_jusuf_ucp_64nx1c_512B_1Msg_Serial.pdf](https://gitlab.jsc.fz-juelich.de/cstao-public/linktest/uploads/4f95c810fbde680d7d92551cb7e65c3e/linktest_jusuf_ucp_64nx1c_512B_1Msg_Serial.pdf)
+
+[linktest_jusuf_ucp_64nx1c_512B_3Warm.pdf](https://gitlab.jsc.fz-juelich.de/cstao-public/linktest/uploads/5fb8f26d40d4de586e8407313663d462/linktest_jusuf_ucp_64nx1c_512B_3Warm.pdf)
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