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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Paul Menzel <pmenzel@molgen.mpg.de>
Cc:     linux-kernel@vger.kernel.org, x86@kernel.org,
        David Woodhouse <dwmw2@infradead.org>,
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Subject: Re: [patch 00/37] cpu/hotplug, x86: Reworked parallel CPU bringup
In-Reply-To: <bd5a6a93-def1-9248-2258-c3d3b40071ef@molgen.mpg.de>
References: <20230414225551.858160935@linutronix.de>
 <8247ce4d-15b7-03b2-0c9b-74f8cd6cad50@molgen.mpg.de> <87wn2a4la5.ffs@tglx>
 <bd5a6a93-def1-9248-2258-c3d3b40071ef@molgen.mpg.de>
Date:   Tue, 18 Apr 2023 08:58:32 +0200
Message-ID: <87ttxd4qxz.ffs@tglx>
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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)
>>> [=E2=80=A6]
>>> [    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
>>=20
>> Weird. CPU1 fails to come up and report that it has reached the
>> synchronization point.
>>=20
>> Does it work when you add cpuhp.parallel=3Doff on the kernel command lin=
e?
>
> Yes, the ten seconds delay is gone with `cpuhp.parallel=3Doff`.
>
> There was a patch set in the past, that worked on that device. I think=20
> up to v4 it did *not* work at all and hung [1]. I need some days to=20
> 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);
 	}
 }
=20