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=qF8Z2VjJyQZ6XO8aBlAJxFRrxsPQX0ZVwqse6ZSHx0JNqVhb1izyoizTZGgL5hEme+pA GbY6VWmIOPso0uxrab1qIzAACvQ4C5I3Xoy6tVdmaYiZXvBGzUuJcFV00MgcYGgtRijGU egVrE3p3TC5khfXwUiCPXYfo0u6PUt4gg2vH2EfYuxS7ByNd5qg71o4x04ToNFNitHVjH Do6pFgLPsfiYoE1Rlo/5ac7uqoxKHGKKUw/sXX5ge0e4fpKiVjUdecMSxvNzdSE+VdycB 9lv5VQf+lpKxewm5UGJW7qoaBUJMAGslC+ofxglmtCurG0pOa/Tl3VXjaLmlNCs1fpA== 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=FpFtptiJY3xHFKY3kD4yGsGKVOh2ThdjM4McXISEg+rXqEYuq8VZX/CeS+ssb+yJcZ3M Jz0KC1rWP+EYWhQ/SdIUV+EzB6qnZeGRmIEcEu3zqbspEFn0opNMaHOdvNwF6DSxzcuL/ QxVOcTEm96895mwiLwRqHzxSrrBPUSy5UBiNSYy5uzGL/w1yl2//XrhbBReYKtfudhs9J M9sI1sIG+7lyctW1B9msVuBUO2SEMtocI6g/FRXkgNESJ2BdDN0TWleI0BHlF68meBirO Xn3Xoh+SQKwKIyKBAfaWSgzYVCop8N5hhVL1FTLxmvndPeB0cKJDCFGIQiCXvAKeeBw== 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 2F076606D80E for ; Wed, 4 Nov 2026 01:41:37 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 2F076606D80E 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: /TKcFNuMT+6Ws4sIANNWow== X-CSE-MsgGUID: 5Z/jlHzYTnaBVpuvCvZatw== X-IronPort-AV: E=McAfee;i="6800,10657,11955"; a="2509026" X-IronPort-AV: E=Sophos;i="6.27,194,1787036400"; d="scan'208";a="2509026" 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: llvm@lists.linux.dev 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