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Subject: Re: [RFC v2 1/6] x86: introduce kernel restartable sequence
From:   Nadav Amit <nadav.amit@gmail.com>
In-Reply-To: <20190103234029.GH6118@tassilo.jf.intel.com>
Date:   Thu, 3 Jan 2019 15:56:34 -0800
Cc:     Ingo Molnar <mingo@redhat.com>, Andy Lutomirski <luto@kernel.org>,
        Peter Zijlstra <peterz@infradead.org>,
        Josh Poimboeuf <jpoimboe@redhat.com>,
        Edward Cree <ecree@solarflare.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        LKML <linux-kernel@vger.kernel.org>, X86 ML <x86@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Borislav Petkov <bp@alien8.de>,
        David Woodhouse <dwmw@amazon.co.uk>
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References: <20181231072112.21051-1-namit@vmware.com>
 <20181231072112.21051-2-namit@vmware.com> <87va35e61a.fsf@linux.intel.com>
 <263A441C-F062-491F-9E95-F00FA2092A99@gmail.com>
 <20190103224835.GG6118@tassilo.jf.intel.com>
 <28F28C02-1817-4A0A-B488-216FDF22169A@gmail.com>
 <20190103234029.GH6118@tassilo.jf.intel.com>
To:     Andi Kleen <ak@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
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> On Jan 3, 2019, at 3:40 PM, Andi Kleen <ak@linux.intel.com> wrote:
>=20
>> Thanks for the explanations. I don=E2=80=99t think it would work =
(e.g., IRQs). I can
>> avoid generalizing and just detect the "magic sequence=E2=80=9D of =
the code, but let
>> me give it some more thought.
>=20
> If you ask me I would just use compiler profile feedback or autofdo =
(if your
> compiler has a working version)
>=20
> The compiler can do a much better job at optimizing this than you ever =
could.
>=20
> Manual FDO needs some kernel patching though.

As long as you are willing to profile and build your own kernels. =
(Profiling
will not tell you if users are about to use IPv4/6).

I also don=E2=80=99t see how FDO can support modules.