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Odroid XU4 Memcopy Slow on all Kernel 5.x 80MB/sec instead of 370+MB/sec

Description

Kernel 4.14.186 – Fast. http://ix.io/2qxh

Kernel 5.4 – Slow

Kernel 5.7 – Slow http://ix.io/2qpX

odroid forum site admin thinks DRAM controller config could have issues on kernel 5
https://forum.odroid.com/viewtopic.php?f=184&t=38774

Additional research…

this patch for dynaminc timings was added around kernel 5.3 https://lwn.net/Articles/787647/

we’re using it

Environment

None

Activity

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Lane Jennison
June 30, 2020, 2:32 PM

Improved on Kernel 5.4 as well http://ix.io/2qzC

Lane Jennison
June 30, 2020, 2:55 PM

Merged Workaround

Werner
July 3, 2020, 4:59 AM

https://github.com/armbian/build/pull/2073#issuecomment-653324886

Revert and add govenor adjustment to the build script instead?

Lane Jennison
July 3, 2020, 10:49 AM

I think we should leave as is.

Tony made a good point that the issue is a defect, not a bad default configuration https://freenode.irclog.whitequark.org/armbian/2020-07-03#27409192

Typically tweaks via build scripts are done in the spirit of performance tuning on top a otherwise working default.

I think we should make a new ticket to follow-up periodically and re-enable whenever upstream or a patchset makes the governor work as intended

Tony McKahan
July 3, 2020, 6:06 PM

I agree with Lane, something is wrong with the driver/kernel to cause the behavior, I'd rather see it omitted for now

Assignee

Lane Jennison

Reporter

Lane Jennison

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Priority

High
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