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From:   Thomas Gleixner <tglx@linutronix.de>
To:     Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc:     linux-kernel <linux-kernel@vger.kernel.org>, x86 <x86@kernel.org>,
        paulmck <paulmck@kernel.org>, Andy Lutomirski <luto@kernel.org>,
        Alexandre Chartre <alexandre.chartre@oracle.com>,
        Frederic Weisbecker <frederic@kernel.org>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Petr Mladek <pmladek@suse.com>, rostedt <rostedt@goodmis.org>,
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        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Juergen Gross <jgross@suse.com>,
        Brian Gerst <brgerst@gmail.com>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Will Deacon <will@kernel.org>
Subject: Re: [patch V4 part 1 14/36] x86/entry: Get rid of ist_begin/end_non_atomic()
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Date:   Fri, 15 May 2020 11:34:50 +0200
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Mathieu Desnoyers <mathieu.desnoyers@efficios.com> writes:

> ----- On May 5, 2020, at 9:16 AM, Thomas Gleixner tglx@linutronix.de wrote:
>
>> This is completely overengineered and definitely not an interface which
>> should be made available to anything else than this particular MCE case.
>
> This patch introduces a significant change under the radar (not explained
> in the changelog): it turns preempt_enable_no_resched() into preempt_enable().
>
> Why, and why was it a no_resched() in the first place ? Was it for performance
> or correctness reasons ?

_no_resched() is an optimization when in code which cannot schedule
anyway. But #MC is definitely not a performance critical hotpath.

So yes, it's a change but really not significant.

>> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
>> ---
< Remove useless gunk >

Can you please trim your replies?

Thanks,

        tglx