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From: Andi Kleen <ak@linux.intel.com>
To: Prarit Bhargava <prarit@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>,
	linux-kernel@vger.kernel.org, Ingo Molnar <mingo@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	x86@kernel.org, Peter Zijlstra <peterz@infradead.org>,
	Dave Hansen <dave.hansen@intel.com>,
	Piotr Luc <piotr.luc@intel.com>, Kan Liang <kan.liang@intel.com>,
	Borislav Petkov <bp@suse.de>,
	Stephane Eranian <eranian@google.com>,
	Arvind Yadav <arvind.yadav.cs@gmail.com>,
	Andy Lutomirski <luto@kernel.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
	Tom Lendacky <thomas.lendacky@amd.com>,
	He Chen <he.chen@linux.intel.com>,
	Mathias Krause <minipli@googlemail.com>,
	Tim Chen <tim.c.chen@linux.intel.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Subject: Re: [PATCH v5 2/3] x86/topology: Avoid wasting 128k for package id array
Date: Fri, 10 Nov 2017 07:01:12 -0800	[thread overview]
Message-ID: <20171110150112.GI8522@tassilo.jf.intel.com> (raw)
In-Reply-To: <372083ad-2a77-4646-bc67-dd4348a521d9@redhat.com>

> > All of that works. There is no way to make sure that a lookup is fully
> > serialized against a concurrent update. Even if the lookup holds
> > cpu_read_lock() the new package might arrive right after the unlock.
> > 
> 
> Thanks Thomas.
> 
> Andi, do you want to take a look at this?

I was originally worried about races, that is why i tried to put 
everything into cpu_data. But that didn't work out because something
clears it. Perhaps the right solution would be some extra per_cpu
data variables, and search for the first match. I suspect that would
be simpler. But if that doesn't work I guess something like Thomas'
example will work.

I assume you will handle it, Prarit?

-Andi

  parent reply	other threads:[~2017-11-10 15:01 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-11-05 16:54 [PATCH v5 0/3] Fix panic in logical packages calculation Prarit Bhargava
2017-11-05 16:54 ` [PATCH v5 1/3] perf/x86/intel/uncore: Cache logical pkg id in uncore driver Prarit Bhargava
2017-11-07 22:19   ` Thomas Gleixner
2017-11-05 16:54 ` [PATCH v5 2/3] x86/topology: Avoid wasting 128k for package id array Prarit Bhargava
2017-11-10  0:43   ` Thomas Gleixner
2017-11-10 12:29     ` Prarit Bhargava
2017-11-10 12:52       ` Thomas Gleixner
2017-11-10 12:56         ` Thomas Gleixner
2017-11-10 15:01       ` Andi Kleen [this message]
2017-11-10 18:35         ` Prarit Bhargava
2017-11-10 19:39           ` Andi Kleen
2017-11-12 13:36         ` Thomas Gleixner
2017-11-12 16:55           ` Prarit Bhargava
2017-11-10  2:42   ` [lkp-robot] [x86/topology] 4b5ebf8be9: BUG:KASAN:slab-out-of-bounds kernel test robot
2017-11-10  2:42     ` kernel test robot
2017-11-05 16:54 ` [PATCH v5 3/3] x86/smpboot: Fix __max_logical_packages estimate Prarit Bhargava

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