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

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Date:   Tue, 18 Apr 2023 08:58:32 +0200
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     linux-kernel@...r.kernel.org, x86@...nel.org,
        David Woodhouse <dwmw2@...radead.org>,
        Andrew Cooper <andrew.cooper3@...rix.com>,
        Brian Gerst <brgerst@...il.com>,
        Arjan van de Veen <arjan@...ux.intel.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Paul McKenney <paulmck@...nel.org>,
        Tom Lendacky <thomas.lendacky@....com>,
        Sean Christopherson <seanjc@...gle.com>,
        Oleksandr Natalenko <oleksandr@...alenko.name>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        Piotr Gorski <lucjan.lucjanov@...il.com>,
        David Woodhouse <dwmw@...zon.co.uk>,
        Usama Arif <usama.arif@...edance.com>,
        Jürgen Groß <jgross@...e.com>,
        Boris Ostrovsky <boris.ostrovsky@...cle.com>,
        xen-devel@...ts.xenproject.org,
        Russell King <linux@...linux.org.uk>,
        Arnd Bergmann <arnd@...db.de>,
        linux-arm-kernel@...ts.infradead.org,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <will@...nel.org>, Guo Ren <guoren@...nel.org>,
        linux-csky@...r.kernel.org,
        Thomas Bogendoerfer <tsbogend@...ha.franken.de>,
        linux-mips@...r.kernel.org,
        "James E. J. Bottomley" <James.Bottomley@...senPartnership.com>,
        Helge Deller <deller@....de>, linux-parisc@...r.kernel.org,
        Paul Walmsley <paul.walmsley@...ive.com>,
        Palmer Dabbelt <palmer@...belt.com>,
        linux-riscv@...ts.infradead.org,
        Mark Rutland <mark.rutland@....com>,
        Sabin Rapan <sabrapan@...zon.com>
Subject: Re: [patch 00/37] cpu/hotplug, x86: Reworked parallel CPU bringup

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);
 	}
 }