linux-kernel - Re: [PATCH 2/2] x86/microcode: Fix CPU synchronization routine

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Message-ID: <20180315010014.xsedkarzrgqiunxf@khazad-dum.debian.net>
Date:   Wed, 14 Mar 2018 22:00:14 -0300
From:   Henrique de Moraes Holschuh <hmh@....eng.br>
To:     Borislav Petkov <bp@...en8.de>
Cc:     X86 ML <x86@...nel.org>, Emanuel Czirai <xftroxgpx@...tonmail.com>,
        Ashok Raj <ashok.raj@...el.com>,
        Tom Lendacky <thomas.lendacky@....com>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] x86/microcode: Fix CPU synchronization routine

On Wed, 14 Mar 2018, Borislav Petkov wrote:
> Also, since the update is serialized and it also takes a couple of
> thousand cycles per microcode engine, increase the exit timeout by the
> number of CPUs on the system.

Maybe on AMD it is that fast ;-)

Intel takes anything from twenty thousand cycles to several *million*
cycles per core, proportional to microcode update size.

-- 
  Henrique Holschuh