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Date: Wed, 7 Feb 2018 17:25:07 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>, x86@kernel.org,
        Tom Lendacky <thomas.lendacky@amd.com>,
        Dave Hansen <dave.hansen@intel.com>, Andy Lutomirski <luto@kernel.org>,
        Borislav Petkov <bp@suse.de>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [RFC 0/3] x86: Patchable constants
Message-ID: <20180207162507.GB25219@hirez.programming.kicks-ass.net>
References: <20180207145913.2703-1-kirill.shutemov@linux.intel.com>
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On Wed, Feb 07, 2018 at 05:59:10PM +0300, Kirill A. Shutemov wrote:
> This conversion makes GCC generate worse code. Conversion __PHYSICAL_MASK
> to a patchable constant adds about 5k in .text on defconfig and makes it
> slightly slower at runtime (~0.2% on my box).

Do you have explicit examples for the worse code? That might give clue
on how to improve things.