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SubjectRe: [RFC v3 0/2] CPU-Idle latency selftest framework
Hi Pratik,

I tried V3 on a Intel i5-10600K processor with 6 cores and 12 CPUs.
The core to cpu mappings are:
core 0 has cpus 0 and 6
core 1 has cpus 1 and 7
core 2 has cpus 2 and 8
core 3 has cpus 3 and 9
core 4 has cpus 4 and 10
core 5 has cpus 5 and 11

By default, it will test CPUs 0,2,4,6,10 on cores 0,2,4,0,2,4.
wouldn't it make more sense to test each core once?
With the source CPU always 0, I think the results from the results
from the destination CPUs 0 and 6, on core 0 bias the results, at
least in the deeper idle states. They don't make much difference in
the shallow states. Myself, I wouldn't include them in the results.
Example, where I used the -v option for all CPUs:

--IPI Latency Test---
--Baseline IPI Latency measurement: CPU Busy--
SRC_CPU DEST_CPU IPI_Latency(ns)
0 0 101
0 1 790
0 2 609
0 3 595
0 4 737
0 5 759
0 6 780
0 7 741
0 8 574
0 9 681
0 10 527
0 11 552
Baseline Avg IPI latency(ns): 620 <<<< suggest 656 here
---Enabling state: 0---
SRC_CPU DEST_CPU IPI_Latency(ns)
0 0 76
0 1 471
0 2 420
0 3 462
0 4 454
0 5 468
0 6 453
0 7 473
0 8 380
0 9 483
0 10 492
0 11 454
Expected IPI latency(ns): 0
Observed Avg IPI latency(ns) - State 0: 423 <<<<< suggest 456 here
---Enabling state: 1---
SRC_CPU DEST_CPU IPI_Latency(ns)
0 0 112
0 1 866
0 2 663
0 3 851
0 4 1090
0 5 1314
0 6 1941
0 7 1458
0 8 687
0 9 802
0 10 1041
0 11 1284
Expected IPI latency(ns): 1000
Observed Avg IPI latency(ns) - State 1: 1009 <<<< suggest 1006 here
---Enabling state: 2---
SRC_CPU DEST_CPU IPI_Latency(ns)
0 0 75
0 1 16362
0 2 16785
0 3 19650
0 4 17356
0 5 17606
0 6 2217
0 7 17958
0 8 17332
0 9 16615
0 10 17382
0 11 17423
Expected IPI latency(ns): 120000
Observed Avg IPI latency(ns) - State 2: 14730 <<<< suggest 17447 here
---Enabling state: 3---
SRC_CPU DEST_CPU IPI_Latency(ns)
0 0 103
0 1 17416
0 2 17961
0 3 16651
0 4 17867
0 5 17726
0 6 2178
0 7 16620
0 8 20951
0 9 16567
0 10 17131
0 11 17563
Expected IPI latency(ns): 1034000
Observed Avg IPI latency(ns) - State 3: 14894 <<<< suggest 17645 here

Hope this helps.

... Doug

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