Re: [patch 00/37] cpu/hotplug, x86: Reworked parallel CPU bringup

Thomas Gleixner
2023-04-18T06:58:39Z

Paul!

On Mon, Apr 17 2023 at 19:40, Paul Menzel wrote:
> Am 17.04.23 um 16:48 schrieb Thomas Gleixner:
>
>> On Mon, Apr 17 2023 at 13:19, Paul Menzel wrote:
>>> Am 15.04.23 um 01:44 schrieb Thomas Gleixner:
>>> [ 0.258193] smpboot: CPU0: AMD A6-6400K APU with Radeon(tm) HD
>>> Graphics (family: 0x15, model: 0x13, stepping: 0x1)
>>> […]
>>> [ 0.259329] smp: Bringing up secondary CPUs ...
>>> [ 0.259527] x86: Booting SMP configuration:
>>> [ 0.259528] .... node #0, CPUs: #1
>>> [ 0.261007] After schedule_preempt_disabled
>>> [ 10.260990] CPU1 failed to report alive state
>>
>> Weird. CPU1 fails to come up and report that it has reached the
>> synchronization point.
>>
>> Does it work when you add cpuhp.parallel=off on the kernel command line?
>
> Yes, the ten seconds delay is gone with `cpuhp.parallel=off`.
>
> There was a patch set in the past, that worked on that device. I think
> up to v4 it did *not* work at all and hung [1]. I need some days to
> collect the results again.

Can you please apply the patch below on top of the pile remove the
command line option again?

Thanks,

tglx
---
kernel/cpu.c | 1 +
1 file changed, 1 insertion(+)

--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -1777,6 +1777,7 @@ static void __init cpuhp_bringup_mask(co
*/
WARN_ON(cpuhp_invoke_callback_range(false, cpu, st, CPUHP_OFFLINE));
}
+ msleep(20);
}
}