linux-kernel - Re: [PATCH 0/2 v3] cpu hotplug: Preserve topology directory after soft remove event

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Message-ID: <20160928064823.GR2794@worktop>
Date:   Wed, 28 Sep 2016 08:48:23 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Prarit Bhargava <prarit@...hat.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Borislav Petkov <bp@...e.de>, linux-kernel@...r.kernel.org,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Len Brown <len.brown@...el.com>,
        Andi Kleen <ak@...ux.intel.com>, Jiri Olsa <jolsa@...hat.com>,
        Juergen Gross <jgross@...e.com>
Subject: Re: [PATCH 0/2 v3] cpu hotplug: Preserve topology directory after
 soft remove event

On Tue, Sep 27, 2016 at 11:26:14AM -0400, Prarit Bhargava wrote:
> I see now that the issue is not understanding the difference between physical
> and soft thread removal.  I will write that up and get back to everyone.

You don't seem to understand that from the kernels POV there is no such
distinction.

There is only one unplug operation that caters to both cases. Therefore
unplug needs to assume the most stringent (ie. physical) for things to
work right.

There is no 'soft thread removal', except maybe in the userspace API,
you're the one that is confused.