From: Uladzislau Rezki <urezki@gmail.com>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Uladzislau Rezki <urezki@gmail.com>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org,
Andrew Morton <akpm@linux-foundation.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
GregKroah-Hartmangregkh@linuxfoundation.org
Subject: Re: nr_cpu_ids vs AMD 3970x(32 physical CPUs)
Date: Fri, 3 Jul 2020 19:09:41 +0200 [thread overview]
Message-ID: <20200703170941.GA4372@pc636> (raw)
In-Reply-To: <20200703165627.GG4781@hirez.programming.kicks-ass.net>
On Fri, Jul 03, 2020 at 06:56:27PM +0200, Peter Zijlstra wrote:
> On Fri, Jul 03, 2020 at 05:57:49PM +0200, Uladzislau Rezki wrote:
> > Hello, folk.
> >
> > I have a system based on AMD 3970x CPUs. It has 32 physical cores
> > and 64 threads. It seems that "nr_cpu_ids" variable is not correctly
> > set on latest 5.8-rc3 kernel. Please have a look below on dmesg output:
> >
> > <snip>
> > urezki@pc638:~$ sudo dmesg | grep 128
> > [ 0.000000] IOAPIC[0]: apic_id 128, version 33, address 0xfec00000, GSI 0-23
> > [ 0.000000] smpboot: Allowing 128 CPUs, 64 hotplug CPUs
>
> This is your BIOS saying it needs 128 ids, 64 of which are 'empty'.
>
> I have a box like that as well, if it bothers you boot with:
> "possible_cpus=64" or something.
>
OK, i got it. I thought that "cpu_possible_mask" strictly follows
the rule: the number of CPUs in a system that physically are present.
Thanks, Peter!
--
Vlad Rezki
next prev parent reply other threads:[~2020-07-03 17:09 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-03 15:57 nr_cpu_ids vs AMD 3970x(32 physical CPUs) Uladzislau Rezki
2020-07-03 16:56 ` Peter Zijlstra
2020-07-03 17:09 ` Uladzislau Rezki [this message]
2020-07-03 17:38 ` Peter Zijlstra
2020-07-03 19:26 ` Uladzislau Rezki
2020-07-03 17:07 ` Gabriel C
2020-07-03 17:24 ` Uladzislau Rezki
2020-07-03 17:45 ` Peter Zijlstra
2020-07-03 18:36 ` Gabriel C
2020-07-03 19:05 ` peter enderborg
2020-07-03 19:28 ` Uladzislau Rezki
2020-07-03 20:08 ` Linus Torvalds
2020-07-03 21:20 ` Uladzislau Rezki
2020-07-03 21:51 ` Matthew Wilcox
2020-07-03 22:22 ` Uladzislau Rezki
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