Date: Tue, 28 Jul 2015 10:28:39 -0500
From: Josh Poimboeuf <jpoimboe@redhat.com>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Thomas Gleixner <tglx@linutronix.de>, Ingo Molnar <mingo@redhat.com>,
        "H. Peter Anvin" <hpa@zytor.com>, Michal Marek <mmarek@suse.cz>,
        Peter Zijlstra <peterz@infradead.org>,
        Andy Lutomirski <luto@kernel.org>, Borislav Petkov <bp@alien8.de>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Andi Kleen <andi@firstfloor.org>, Pedro Alves <palves@redhat.com>,
        Namhyung Kim <namhyung@gmail.com>,
        Bernd Petrovitsch <bernd@petrovitsch.priv.at>, X86 ML <x86@kernel.org>,
        live-patching@vger.kernel.org,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH v8 09/21] x86/paravirt: Align paravirt thunk functions at
 16-byte boundaries
Message-ID: <20150728152839.GA6737@treble.redhat.com>
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 <CALCETrX4aBxf_apw8oqb_jM_NWp4mSa_8enP_zwF_DX01Dnsiw@mail.gmail.com>
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On Tue, Jul 28, 2015 at 08:23:04AM -0700, Andy Lutomirski wrote:
> On Tue, Jul 28, 2015 at 7:47 AM, Josh Poimboeuf <jpoimboe@redhat.com> wrote:
> > Paravirt thunk functions aren't aligned, which can impact performance
> > and is inconsistent with gcc-generated functions.
> >
> > Align them at 16-byte boundaries to be consistent with gcc functions.
> 
> IMO stackvalidate shouldn't warn about this.  We've discussed dropping
> the alignment requirement entirely, since it seems to have little
> benefit on modern CPUs.

Stackvalidate didn't actually find this alignment issue.  I just noticed
it when fixing the frame pointer issue.  If alignment no longer helps
with performance on modern CPUS, it's fine to drop this patch.

-- 
Josh
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