* Re: [BUG?] Possible scheduler bug on Rock 5B RK3588 on 7.2.5
2026-09-18 1:21 ` [BUG?] Possible scheduler bug on Rock 5B RK3588 on 7.2.5 Chaoyi Chen
@ 2026-09-18 5:03 ` No SPAM here
2026-09-18 16:11 ` No SPAM here
1 sibling, 0 replies; 4+ messages in thread
From: No SPAM here @ 2026-09-18 5:03 UTC (permalink / raw)
To: Chaoyi Chen; +Cc: Peter Zijlstra, linux-arm-kernel
[-- Attachment #1: Type: text/plain, Size: 2586 bytes --]
Thanks Chaoyi, Hello Peter.
I have run `openssl speed -multi 8 rsa md5 sha256 sha512 aes sha1 camellia des rmd160` while booted to the same 6.18.52 kernel, one built with CONFIG_SCHED_CLUSTER=y and one with it =n. This produces a lot of output and runs for about 8.5 minutes and puts out a 21 line table of statistics. I've compared a fair few of the numbers from both runs and most of the numbers from the cluster=n run are between 8 and 11% higher which seems to back up the idea that it's just not using one whole core of the 8 available. I've attached the two 21 line summaries here, CLUSTER=n results are in openssl-speed-nocluster.txt and CLUSTER=y in openssl-speed-cluster.txt.
Trevor
On Friday, 18 September 2026 at 02:22, Chaoyi Chen <chaoyi.chen@rock-chips.com> wrote:
> On 9/18/2026 3:15 AM, No SPAM here wrote:
> > Hi
> >
> > On Thursday, 17 September 2026 at 03:37, Chaoyi Chen <chaoyi.chen@rock-chips.com> wrote:
> >
> >> Hello Trevor,
> >>
> >> On 9/17/2026 9:21 AM, No SPAM here wrote:
> >>>> Would you mind trying to disable `CONFIG_SCHED_CLUSTER` and checking whether
> >>>> the problem still reproduces?
> >
> > trevor@rock-5b:~$ uname -a
> > Linux rock-5b 6.18.52-current-rockchip64 #1 SMP PREEMPT Mon Sep 14 11:36:19 UTC 2026 aarch64 GNU/Linux
> > trevor@rock-5b:~$ grep CONFIG_SCHED_CLU /boot/config-6.18.52-current-rockchip64
> > # CONFIG_SCHED_CLUSTER is not set
> > trevor@rock-5b:~$ sar | tail -5
> >
> > 18:50:15 CPU %user %nice %system %iowait %steal %idle
> > 19:00:15 all 99.89 0.00 0.11 0.00 0.00 0.00
> > 19:10:15 all 99.89 0.00 0.11 0.00 0.00 0.00
> > Average: all 99.89 0.00 0.11 0.00 0.00 0.00
> >
> > Been running stress --cpu 8 since 18:47 and so far it is using all 8 cores at 100%. It would normally have shown the 7/8ths problem after 20s or so, maybe 2 or 3 minutes at max. So I'd say this setting is definitely involved.
> >
>
> Thank you very much for testing. I'm not a scheduler expert, but I see
> that CONFIG_SCHED_CLUSTER is enabled by default on arm64 [0].
>
> Peter is the maintainer and author of this series.
> @Peter, do you have any further insights? Thank you!
>
> This thread background is here[1].
>
> [0]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7bd291abe2da09f59dca81f35a4ec220e5e138a2
> [1]: https://lore.kernel.org/all/f15f8166-c1e4-45dc-9ddd-4ec887e415eb@gdead.co.uk/
>
> --
> Best,
> Chaoyi
>
[-- Attachment #2: openssl-speed-nocluster.txt --]
[-- Type: text/plain, Size: 1933 bytes --]
md5 206646.70k 682082.69k 1627733.76k 2515694.25k 3003411.11k 3047533.23k
sha1 257265.18k 945564.91k 2826501.12k 5732223.32k 8417888.94k 8727172.44k
rmd160 168775.57k 482578.01k 1047489.96k 1490576.73k 1703146.84k 1721171.97k
sha256 256593.18k 949375.79k 2850635.69k 5781916.67k 8441995.26k 8740929.54k
sha512 139462.71k 558478.93k 1124027.14k 1811831.47k 2209688.23k 2246688.77k
des-cbc 0.00 0.00 0.00 0.00 0.00 0.00
des-ede3 132712.38k 138286.40k 139840.77k 140261.44k 140372.65k 140245.64k
aes-128-cbc 2887098.42k 6649536.64k 10139807.06k 11986084.86k 12734630.57k 12803970.39k
aes-192-cbc 2751396.09k 5874383.27k 8473588.05k 9655262.55k 10161837.40k 10203824.13k
aes-256-cbc 2674905.48k 5340891.67k 7373585.83k 8255187.97k 8579080.19k 8609371.48k
camellia-128-cbc 582227.33k 679838.68k 710770.01k 721328.47k 723978.92k 724489.56k
camellia-192-cbc 468416.18k 530513.96k 550038.44k 556270.25k 557826.05k 558000.81k
camellia-256-cbc 467775.22k 530535.47k 550066.77k 556213.59k 556876.29k 557940.74k
sign verify encrypt decrypt sign/s verify/s encr./s decr./s
rsa 512 bits 0.000016s 0.000001s 0.000002s 0.000017s 64304.1 755378.7 645816.8 57525.3
rsa 1024 bits 0.000083s 0.000004s 0.000005s 0.000086s 11990.6 233562.6 218317.7 11679.9
rsa 2048 bits 0.000571s 0.000016s 0.000016s 0.000574s 1752.4 64301.8 62614.2 1743.0
rsa 3072 bits 0.001760s 0.000034s 0.000035s 0.001765s 568.1 29361.9 28935.6 566.5
rsa 4096 bits 0.003995s 0.000060s 0.000060s 0.004000s 250.3 16738.8 16563.8 250.0
rsa 7680 bits 0.031106s 0.000207s 0.000208s 0.031131s 32.1 4839.0 4814.8 32.1
rsa 15360 bits 0.189898s 0.000820s 0.000821s 0.184244s 5.3 1219.4 1217.3 5.4
[-- Attachment #3: openssl-speed-cluster.txt --]
[-- Type: text/plain, Size: 1933 bytes --]
md5 207893.48k 681828.80k 1624703.66k 2514480.47k 3003370.15k 3047145.47k
sha1 257001.97k 944134.21k 2818819.67k 5729986.56k 8258613.03k 7898929.54k
rmd160 157569.82k 446793.28k 963480.75k 1360659.80k 1549350.23k 1565089.82k
sha256 241875.40k 894078.82k 2667497.15k 5343714.37k 7705458.01k 7961350.38k
sha512 130139.93k 520255.22k 1040071.77k 1665936.38k 2023230.12k 2055602.18k
des-cbc 0.00 0.00 0.00 0.00 0.00 0.00
des-ede3 122223.67k 126929.64k 128361.86k 128859.14k 128809.72k 128849.24k
aes-128-cbc 2737165.32k 6205807.32k 9220290.30k 10736674.05k 11360862.21k 11410365.80k
aes-192-cbc 2609197.06k 5462457.41k 7717889.27k 8693462.87k 9127941.46k 9163740.50k
aes-256-cbc 2531961.38k 4973017.60k 6722701.40k 7453166.55k 7728204.46k 7748107.85k
camellia-128-cbc 537508.58k 621512.36k 648128.60k 655762.20k 658434.73k 658625.88k
camellia-192-cbc 433255.91k 484146.24k 500183.47k 506022.57k 507199.49k 507164.29k
camellia-256-cbc 430679.27k 483797.80k 500581.66k 505632.77k 507202.22k 507150.34k
sign verify encrypt decrypt sign/s verify/s encr./s decr./s
rsa 512 bits 0.000017s 0.000001s 0.000002s 0.000019s 58896.7 690687.0 594987.3 52892.2
rsa 1024 bits 0.000092s 0.000005s 0.000005s 0.000094s 10854.4 211381.1 198357.9 10589.4
rsa 2048 bits 0.000633s 0.000017s 0.000018s 0.000636s 1580.0 57918.6 56515.5 1573.2
rsa 3072 bits 0.001957s 0.000038s 0.000038s 0.001959s 511.0 26431.1 26051.8 510.3
rsa 4096 bits 0.004442s 0.000066s 0.000067s 0.004449s 225.1 15041.4 14899.8 224.8
rsa 7680 bits 0.034616s 0.000230s 0.000231s 0.034496s 28.9 4351.1 4323.8 29.0
rsa 15360 bits 0.211541s 0.000911s 0.000917s 0.211495s 4.7 1097.8 1090.9 4.7
^ permalink raw reply [flat|nested] 4+ messages in thread* Re: [BUG?] Possible scheduler bug on Rock 5B RK3588 on 7.2.5
2026-09-18 1:21 ` [BUG?] Possible scheduler bug on Rock 5B RK3588 on 7.2.5 Chaoyi Chen
2026-09-18 5:03 ` No SPAM here
@ 2026-09-18 16:11 ` No SPAM here
2026-09-19 10:57 ` Chaoyi Chen
1 sibling, 1 reply; 4+ messages in thread
From: No SPAM here @ 2026-09-18 16:11 UTC (permalink / raw)
To: Chaoyi Chen; +Cc: Peter Zijlstra, linux-arm-kernel
I have now retested with kernel 7.3.0-rc3 and this bug appears to have been fixed. The same command now runs all 8 cores at 100% for the duration of the test and the resulting numbers differ (in favour of the 6.18.52 CLUSTER=n kernel) by a maximum of 0.25% which is measurement error.
Thanks for your attention. This can be marked as solved.
Trevor
Sent with Proton Mail secure email.
On Friday, 18 September 2026 at 02:22, Chaoyi Chen <chaoyi.chen@rock-chips.com> wrote:
> On 9/18/2026 3:15 AM, No SPAM here wrote:
> > Hi
> >
> > On Thursday, 17 September 2026 at 03:37, Chaoyi Chen <chaoyi.chen@rock-chips.com> wrote:
> >
> >> Hello Trevor,
> >>
> >> On 9/17/2026 9:21 AM, No SPAM here wrote:
> >>>> Would you mind trying to disable `CONFIG_SCHED_CLUSTER` and checking whether
> >>>> the problem still reproduces?
> >
> > trevor@rock-5b:~$ uname -a
> > Linux rock-5b 6.18.52-current-rockchip64 #1 SMP PREEMPT Mon Sep 14 11:36:19 UTC 2026 aarch64 GNU/Linux
> > trevor@rock-5b:~$ grep CONFIG_SCHED_CLU /boot/config-6.18.52-current-rockchip64
> > # CONFIG_SCHED_CLUSTER is not set
> > trevor@rock-5b:~$ sar | tail -5
> >
> > 18:50:15 CPU %user %nice %system %iowait %steal %idle
> > 19:00:15 all 99.89 0.00 0.11 0.00 0.00 0.00
> > 19:10:15 all 99.89 0.00 0.11 0.00 0.00 0.00
> > Average: all 99.89 0.00 0.11 0.00 0.00 0.00
> >
> > Been running stress --cpu 8 since 18:47 and so far it is using all 8 cores at 100%. It would normally have shown the 7/8ths problem after 20s or so, maybe 2 or 3 minutes at max. So I'd say this setting is definitely involved.
> >
>
> Thank you very much for testing. I'm not a scheduler expert, but I see
> that CONFIG_SCHED_CLUSTER is enabled by default on arm64 [0].
>
> Peter is the maintainer and author of this series.
> @Peter, do you have any further insights? Thank you!
>
> This thread background is here[1].
>
> [0]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=7bd291abe2da09f59dca81f35a4ec220e5e138a2
> [1]: https://lore.kernel.org/all/f15f8166-c1e4-45dc-9ddd-4ec887e415eb@gdead.co.uk/
>
> --
> Best,
> Chaoyi
>
^ permalink raw reply [flat|nested] 4+ messages in thread