From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=192.198.163.17 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793756498; b=J4NQFZmCJ68q394pt6XXUyn4n2ACI8lVGLNYRUkm0tDOJaxj9QXB6YdAGHSNtfqFKTKK kmGGLKlx4Le7rwcq/Uuz3UqnAGcDAmK4v+wy+MnAPcMsPRZkTHvanrd2tVmeLZIXKBKgA jBUWPzGybbHt51NQtPwKR9wuJjHzLGu+Nifv1/FMTCIb74kyN0EZffiy32VV873+sX0bN F42LpCwKE7Xdayk9RT9++uvwNas0AJPGAHyP0Lv8EdliKOZIoLGipsWYszzaGnuksU75p N3iBXhug9KZHO7tIX687ZptNTA+RKUc1aS8ZNqgsShiHsmqpl7BxJp+LGhHcrbKBVbQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793756498; h=DMARC-Filter:DKIM-Signature:X-CSE-ConnectionGUID:X-CSE-MsgGUID: X-IronPort-AV:X-IronPort-AV:Received:X-CSE-ConnectionGUID: X-CSE-MsgGUID:X-ExtLoop1:X-IronPort-AV:Received:Date:From:To:Cc: Subject:Message-ID:References:MIME-Version:Content-Type: Content-Disposition:In-Reply-To; bh=nrEpzo2FbyYGf4WoydGR8O8NAthTAxRR3fiKImw2LBY=; b=MEudNlKSEYHaTgMBbVZESgpknaRKnN8smMTla0MWSaFewiKvCTzcbzs1cB/nJE+Ee1My zyCoQfZ6rUjq4LAOZWGVZYFqewFKAjUCuDqdQeSUAXWThse0U6Oo+ysakqpHksBZLatul oSoz8vvV9Kznwh7nK/m9avT9P2vRvpuQR89wb75FEZz4mc3Xa0+kPRjElvx+zGE13WLRz 3W1c4eoXAMQUcWfrc9EszW44VdSGgQDLgkE4S2my8Z0k6WEkg02SuSmkBKks0KBEPlNQD Fp6AlgY1sXV/vqodWAMiz8uYp1ZJhYz3dHb/xs3bDfPL+yrHLJpDTm9ZLtQR+DoiF1A== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.intel.com; spf=pass smtp.mailfrom=linux.intel.com; dkim=pass header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=c2KAliKC; arc=none smtp.remote-ip=192.198.163.17 Received: from mgamail.intel.com (mgamail.intel.com [192.198.163.17]) (using TLSv1.2 with cipher ECDHE-ECDSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2EFCB606A33A for ; Wed, 4 Nov 2026 01:41:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 2EFCB606A33A Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.intel.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=intel.com header.i=@intel.com header.a=rsa-sha256 header.s=Intel header.b=c2KAliKC DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=intel.com; i=@intel.com; q=dns/txt; s=Intel; t=1793756498; x=1825292498; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=vDr2JILrP7CXpfLgY8bKxkAuyrvod5DOQU34EM2moew=; b=c2KAliKC7pExndXfYaCKkJIJPiMYnKFyeJN/Y5wtwPxWO/stcOJiix58 PbzD4IUAvZCM/DgFjE8PqbYNvuBD1YTJ7Rg2bwhwVY5Vq4sN3fi8QdOzV 4AoHvYSxWwyASzX2IkQaWISfug3KK85T+9/MXwA+eus9VjkXDespwGsU+ ozpLYYsUSnsO/Jf0TzRVBeWdR7u1XeRCExGA+mnY3ttQJBCKv5him0+0Y KB2DRm0OEejZfaj1ZdeE+tm7aXdwd9Us0bb6Vy8GeXwDKya0xDl20C0At wjeUNrojb97FR/9HGwBU8GSKx/H8tRVbrMAuiqJsZ7s1Ej8d1g/K+9UHW Q==; X-CSE-ConnectionGUID: t/h1vc8nSAyNcCyqq461gA== X-CSE-MsgGUID: D3acwIt9RiSrjAH+vBa5Cw== X-IronPort-AV: E=McAfee;i="6800,10657,11955"; a="2509025" X-IronPort-AV: E=Sophos;i="6.27,194,1787036400"; d="scan'208";a="2509025" Received: from fmviesa008.fm.intel.com ([10.60.135.148]) by fmvoesa111.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Nov 2026 17:41:37 -0800 X-CSE-ConnectionGUID: nOdDaauHReGtVTXCAtE9IA== X-CSE-MsgGUID: z881yAwyRF2NYDW1Ta5Bng== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,194,1787036400"; d="scan'208";a="6912924" Received: from tassilo.jf.intel.com (HELO tassilo) ([10.54.38.190]) by smtpauth.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 03 Nov 2026 17:41:37 -0800 Date: Tue, 3 Nov 2026 17:41:35 -0800 From: Andi Kleen To: Martin Leitner-Ankerl Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Peter Zijlstra , Youling Tang , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , llvm@lists.linux.dev, linux-kernel@vger.kernel.org, Youling Tang , Nikolay Borisov Subject: Re: [PATCH] x86/cpu: Use prefetcht0 for prefetch() on 64-bit Message-ID: References: <20261103060658.696994-1-martin.ankerl@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20261103060658.696994-1-martin.ankerl@gmail.com> > +#ifdef CONFIG_X86_64 > +/* > + * Every x86-64 CPU has prefetcht0. Not __builtin_prefetch(): the kernel > + * builds with -mno-sse, and clang then drops the builtin without a warning. > + */ > +static inline void prefetch(const void *x) > +{ > + asm("prefetcht0 %0" : : "m" (*(const char *)x)); > +} > +#else One thing you should check if the inline assembly pessimizes the code on gcc. Normally builtins can be better optimized. Or keep using the builtin on gcc to be safe. -Andi