From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (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 6D67934CFA7; Fri, 6 Feb 2026 08:43:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770367393; cv=none; b=I1ky231ZaRcLOEqMBt06njE+0v2NphgQ+6MqO3WT92+zYhIqvN/xB1jd5cUEwBBEY5pBBJbmk5mqJjMsNBjrUF2h7A6i4LKqUxzUvzbVs/J4uJrFrTO2OKnTsgWHCaCTXGhI6HzpcaFZYPeCcQMX1lQt0JNt6hCorlMvaH/PjbE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1770367393; c=relaxed/simple; bh=aVkVFbpBHuweFBR+QK/0GwjGenduai58ydNn8RqFKHQ=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=qsU/2wU7AZq0+DmuwdiaU850teoGukOyKDHYT3XKIJ6JUOHy2PH7eNLzDZo8Ioq5XImoyljL/r8kFDgSkvkd+8tdNOyncvQz65EY2X0RzIoCx6Lkusix8Whmpv4siAa8pbjYBEAQSrUYLN5j5OZQ937fcNhc1UHsZ7d8PFk4BQU= 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=l83W0Gp4; arc=none smtp.client-ip=90.155.50.34 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="l83W0Gp4" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=VpPg21vAhreDcZaU+61r4auXUZvlgqN6fCq719sJ/UU=; b=l83W0Gp4ZLavHeHFBLB6++hquS Vpcmnncfe9xQ2T0hd6gmZD2RUnEurDqtBw4jhQndWUq0upw/th0/bx4cXOdok/3TsC0Yc3UDOLMll uKEhvamNbIlERr53XsVYzaiqE6tifwGkHH5eW4Rv1Rwg8woyEH41qyWStRikH3xlmpCAR5s1KY5v/ xztLKRhKLgfhFxZybwNE0Vcd5hru5c3x0/2S59rUGIGQsO7WxKKQaQRy+RjCKkoaHoUKqRdnLzZL2 HyFVArUF/oB1UY8INyMHSR7bKZosKs7lH9y+v1yFm/ea/uMvfTMXp/3fkGdJBNM1t5TqT2tVmIt1D R0ZKZzzg==; 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 casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1voHQa-00000004uWd-1gtO; Fri, 06 Feb 2026 08:43:00 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 146C5302DA9; Fri, 06 Feb 2026 09:42:58 +0100 (CET) Date: Fri, 6 Feb 2026 09:42:58 +0100 From: Peter Zijlstra To: Joel Fernandes Cc: Boqun Feng , Lyude Paul , rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Boqun Feng , Daniel Almeida , Miguel Ojeda , Alex Gaynor , Gary Guo , =?iso-8859-1?Q?Bj=F6rn?= Roy Baron , Benno Lossin , Andreas Hindborg , Alice Ryhl , Trevor Gross , Danilo Krummrich , Andrew Morton , Ingo Molnar , Will Deacon , Waiman Long Subject: Re: [PATCH v17 02/16] preempt: Track NMI nesting to separate per-CPU counter Message-ID: <20260206084258.GO1282955@noisy.programming.kicks-ass.net> References: <20260121223933.1568682-1-lyude@redhat.com> <20260121223933.1568682-3-lyude@redhat.com> <20260203121520.GN1282955@noisy.programming.kicks-ass.net> <20260204111234.GA3031506@noisy.programming.kicks-ass.net> <1a332333-0706-4548-8fbe-d65956f70f99@nvidia.com> <44507281-87bc-4548-b542-addf3477921c@nvidia.com> <52c1f833-0967-4692-8275-6d448a104350@nvidia.com> Precedence: bulk X-Mailing-List: rust-for-linux@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: <52c1f833-0967-4692-8275-6d448a104350@nvidia.com> On Thu, Feb 05, 2026 at 08:24:40PM -0500, Joel Fernandes wrote: > > I guess Peter was trying to say it's not a slow path if you consider > > perf event interrupts on x86? [1] > > How are we handling this performance issue then on 32-bit x86 architecture with > perf? Or are we saying we don't care about performance on 32-bit? Yeah, in general I don't consider any 32bit architecture performance critical at this point. Its pure legacy code, to be removed at some point. To x86_32 in particular, we make it limp along. It sorta builds and sorta boots but meh. It doesn't even have most of the speculation fixes. You really, as in *REALLY* should not be running a x86_32 kernel. I mean, if you still want to run Linux on your museum grade Pentium-II processor, don't let me stop you. Just don't expect miracles.