From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0B92F3DCD94 for ; Mon, 23 Mar 2026 20:24:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774297489; cv=none; b=HmnETSoWdGWgoZlR0GeXjO6MjmcCZgbW05mq2x59lXatxrjZ1uilc4T1WTlBbF2TMNdxCCHHBIre1rU6ObgYxhUlc9+Cfs6EtVRRTprc0RjHAQ6oJbovK1u/XmAFLiFZriwW7jWH7JmkANl99hXAr0RCct2tIsaRAUS8dMQHJ5Y= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774297489; c=relaxed/simple; bh=LusZvNIRjTRxVWNUMTsZqdcOV+977u78rYf9+emSmAU=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qL5XVp/a2TX3GVdllgCrUYFsI5rW1X0HqAvFaykT7X8xvKFlKMYLZ/vdQeChYI/6UbkFP2Mui3piIBu5EpTw8RNTHamzzKUv3MgwuQrXFeFK+FszTpX2IB0zc5ZJ47c2VFCpA4QezerQaACmpBv8q80QoqBsoITVHQwAXdw1m7E= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=RIwnAPBm; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="RIwnAPBm" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Lm5jACArLCuShgqzYKeKIQw1ZqddVRztfdg7ftrvbvY=; b=RIwnAPBmHr6BKQy0wNVb+R/B3J F8mreGBYS4pm1KIPbfmYzZbk5+tAQCd/+Abr+hVWhw2sQup95+XmqZBtTEpTjRKacOge6HIhC/jKs V5ijZBGbn11jiKGVekh8V2eq2CRO+8jpZLi8VoqKipTzsii/EoLRlI1CjXbqD2FCCBqtfcnIo7vPJ ha55076IEE/iyFWbnXgX7ZGDfZxOZq1mDYRPU7WG5/TC34g8X/p2LKoZ9pW7VskZBf0fs7f9Sc9Js YjA6yVg0f8XVUnin8684OF/Sgvv7ubRk/NNLbYpD4OhRWCRNToIgBJy3Sd8aOhjqhpRo11YFGF4hA i/MvScqQ==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1w4lpE-00000002XyH-2i0n; Mon, 23 Mar 2026 20:24:36 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id B92DB300312; Mon, 23 Mar 2026 21:24:34 +0100 (CET) Date: Mon, 23 Mar 2026 21:24:34 +0100 From: Peter Zijlstra To: "H. Peter Anvin" Cc: Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kees Cook , Xin Li , "Ahmed S. Darwish" , Sohil Mehta , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] x86/fred: enable FRED by default Message-ID: <20260323202434.GA3738010@noisy.programming.kicks-ass.net> References: <20260323201510.1537333-1-hpa@zytor.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260323201510.1537333-1-hpa@zytor.com> On Mon, Mar 23, 2026 at 01:15:03PM -0700, H. Peter Anvin wrote: > From: H. Peter Anvin (Intel) > > When FRED was added to the mainline kernel, it was set up as an > explicit opt-in due to the risk of regressions before hardware was > available publicly. > > Now, Panther Lake (Core Ultra 300 series) has been released, and > benchmarking by Phoronix has shown that it provides a significant > performance benefit on most workloads: > > https://www.phoronix.com/review/intel-fred-panther-lake > > Accordingly, enable FRED by default if the CPU supports it. FRED can > of course still be disabled via the fred=off command line option. Acked-by: Peter Zijlstra (Intel)