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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

lane@billroyall:~/GIT/build$ fgrep EXYNOS5422 config/kernel/* config/kernel/linux-imx6-current.config:CONFIG_EXYNOS5422_DMC=m config/kernel/linux-odroidxu4-current.config:CONFIG_EXYNOS5422_DMC=y config/kernel/linux-odroidxu4-dev.config:CONFIG_EXYNOS5422_DMC=y

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Tony McKahanJuly 3, 2020 at 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

Lane JennisonJuly 3, 2020 at 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

WernerJuly 3, 2020 at 4:59 AM

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

Revert and add govenor adjustment to the build script instead?

Lane JennisonJune 30, 2020 at 2:55 PM

Lane JennisonJune 30, 2020 at 2:32 PM

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

Memory performance (big.LITTLE cores measured individually): memcpy: 341.0 MB/s memset: 799.0 MB/s memcpy: 2321.8 MB/s memset: 4877.9 MB/s (0.8%)
Done

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Created June 30, 2020 at 4:33 AM
Updated August 16, 2022 at 7:00 PM
Resolved June 30, 2020 at 2:55 PM