From: Thomas Gleixner <tglx@linutronix.de>
To: David Woodhouse <dwmw2@infradead.org>,
Kim Phillips <kim.phillips@amd.com>,
Usama Arif <usama.arif@bytedance.com>,
arjan@linux.intel.com
Cc: mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com,
hpa@zytor.com, x86@kernel.org, pbonzini@redhat.com,
paulmck@kernel.org, linux-kernel@vger.kernel.org,
kvm@vger.kernel.org, rcu@vger.kernel.org, mimoja@mimoja.de,
hewenliang4@huawei.com, thomas.lendacky@amd.com,
seanjc@google.com, pmenzel@molgen.mpg.de,
fam.zheng@bytedance.com, punit.agrawal@bytedance.com,
simon.evans@bytedance.com, liangma@liangbit.com,
Mario Limonciello <Mario.Limonciello@amd.com>
Subject: Re: [PATCH v6 07/11] x86/smpboot: Disable parallel boot for AMD CPUs
Date: Tue, 07 Feb 2023 01:23:48 +0100 [thread overview]
Message-ID: <87pmamwcff.ffs@tglx> (raw)
In-Reply-To: <d3ec562fd2e03c3aef9534f64915a14a8cb89ae1.camel@infradead.org>
On Sat, Feb 04 2023 at 15:40, David Woodhouse wrote:
> On Fri, 2023-02-03 at 13:48 -0600, Kim Phillips wrote:
>> Then:
>>
>> - a Ryzen 3000 (Picasso A1/Zen+) notebook I have access to fails to boot.
>> - Zen 2,3,4-based servers boot fine
>> - a Zen1-based server doesn't boot.
>
> I've changed it to use CPUID 0xb only if we're actually in x2apic mode,
> which Boris tells me won't be the case on Zen1 because that doesn't
> support X2APIC.
Correct.
> When we're not in x2apic mode, we can use CPUID 0x1 because the 8 bits
> of APIC ID we find there are perfectly sufficient.
Is that worth the trouble?
> Even though we *can* support non-X2APIC processors, we *might* want to
> play it safe and not go back that far; only enabling parallel bringup
> on machines with X2APIC which roughly correlates with "lots of CPUs"
> since that's where the benefit is.
The parallel bringup code is complex enough already, so please don't
optimize for the non-interesting case in the first place. When this has
stabilized then the CPUID 0x1 mechanism can be added if anyone thinks
it's interesting. KISS is still the best engineering principle.
Thanks,
tglx
next prev parent reply other threads:[~2023-02-07 0:23 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-02 21:56 [PATCH v6 00/11] Parallel CPU bringup for x86_64 Usama Arif
2023-02-02 21:56 ` [PATCH v6 01/11] x86/apic/x2apic: Fix parallel handling of cluster_mask Usama Arif
2023-02-06 23:20 ` Thomas Gleixner
2023-02-07 10:57 ` David Woodhouse
2023-02-07 11:27 ` David Woodhouse
2023-02-07 14:24 ` Thomas Gleixner
2023-02-07 19:53 ` David Woodhouse
2023-02-07 20:58 ` Thomas Gleixner
2023-02-07 14:22 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 02/11] cpu/hotplug: Move idle_thread_get() to <linux/smpboot.h> Usama Arif
2023-02-06 23:33 ` Thomas Gleixner
2023-02-07 1:24 ` Paul E. McKenney
2023-02-02 21:56 ` [PATCH v6 03/11] cpu/hotplug: Add dynamic parallel bringup states before CPUHP_BRINGUP_CPU Usama Arif
2023-02-06 23:43 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 04/11] x86/smpboot: Reference count on smpboot_setup_warm_reset_vector() Usama Arif
2023-02-06 23:48 ` Thomas Gleixner
[not found] ` <57195f701f6d1d70ec440c9a28cbee4cfb81dc41.camel@amazon.co.uk>
2023-02-07 14:39 ` Thomas Gleixner
2023-02-07 16:50 ` Sean Christopherson
2023-02-07 19:48 ` [EXTERNAL][PATCH " David Woodhouse
2023-02-02 21:56 ` [PATCH v6 05/11] x86/smpboot: Split up native_cpu_up into separate phases and document them Usama Arif
2023-02-06 23:59 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 06/11] x86/smpboot: Support parallel startup of secondary CPUs Usama Arif
2023-02-02 22:30 ` David Woodhouse
2023-02-02 22:50 ` [External] " Usama Arif
2023-02-03 8:14 ` David Woodhouse
2023-02-03 14:41 ` Arjan van de Ven
2023-02-03 18:17 ` Sean Christopherson
2023-02-07 0:07 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 07/11] x86/smpboot: Disable parallel boot for AMD CPUs Usama Arif
2023-02-03 19:48 ` Kim Phillips
[not found] ` <d5ec64236ba75f0d3f3718fb69b2cb9169d8af0a.camel@amazon.co.uk>
2023-02-03 21:45 ` Kim Phillips
2023-02-03 22:25 ` [EXTERNAL][PATCH " David Woodhouse
2023-02-04 9:07 ` [PATCH " David Woodhouse
2023-02-04 10:09 ` David Woodhouse
2023-02-04 15:40 ` David Woodhouse
2023-02-04 18:18 ` Arjan van de Ven
2023-02-04 22:31 ` David Woodhouse
2023-02-05 22:13 ` [External] " Usama Arif
2023-02-06 8:05 ` David Woodhouse
2023-02-06 12:11 ` Usama Arif
2023-02-06 18:07 ` Sean Christopherson
2023-02-06 17:58 ` Kim Phillips
2023-02-07 16:27 ` Kim Phillips
2023-02-07 0:23 ` Thomas Gleixner [this message]
2023-02-07 10:04 ` David Woodhouse
2023-02-07 14:44 ` Thomas Gleixner
2023-02-07 0:09 ` Thomas Gleixner
[not found] ` <cbd9e88e738dc0c479e87121ca82431731905c73.camel@amazon.co.uk>
2023-02-07 14:46 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 08/11] x86/smpboot: Send INIT/SIPI/SIPI to secondary CPUs in parallel Usama Arif
2023-02-07 0:28 ` Thomas Gleixner
2023-02-02 21:56 ` [PATCH v6 09/11] x86/mtrr: Avoid repeated save of MTRRs on boot-time CPU bringup Usama Arif
2023-02-02 21:56 ` [PATCH v6 10/11] x86/smpboot: Serialize topology updates for secondary bringup Usama Arif
2023-02-02 21:56 ` [PATCH v6 11/11] x86/smpboot: reuse timer calibration Usama Arif
2023-02-07 0:31 ` Thomas Gleixner
2023-02-07 23:16 ` Arjan van de Ven
2023-02-07 23:55 ` Thomas Gleixner
2023-02-05 19:17 ` [PATCH v6 00/11] Parallel CPU bringup for x86_64 Russ Anderson
2023-02-06 8:28 ` David Woodhouse
2023-02-06 12:18 ` [External] " Usama Arif
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