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 3A87813D28C for ; Thu, 6 Jun 2024 11:53:33 +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=1717674815; cv=none; b=tNjOSEy7cd3kui5Xujf/dzHsxnSnhzeRulLqWjBlui29vsCBwfbOctac7IGqVMm0yhXE0F5WmC+CEMFEI9CfZnrCxTZ0fpqN9/q+C2clrNVXFLJtL86DcwT1L2TpXgeBwS7+T4ymKyPUOAZGzKn67He8gJV2QsasPtO83eXFrPc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717674815; c=relaxed/simple; bh=MZxV6F75nZKmqUEOUAqMNdx5/blZ0m+jsECgN2bV7os=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=g0QDHUeYHnG/fmXCN7zx4d7o926a0+IHZi0ZKwrbv+Sr8euF4vvy2YB80KznPM2llmDfm7QgxEFVHJRG95uXEb6USo8pEEjc+IPn3xTYcbnYMvxdjc/8ywsgKR+WS6VDL4H41TmYjMEWGKQ+sS4fINbpdDrG7QIUEX2qsFEyrtA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (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=ca9dmr/p; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (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="ca9dmr/p" 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=MZxV6F75nZKmqUEOUAqMNdx5/blZ0m+jsECgN2bV7os=; b=ca9dmr/pLETq/5NICsLXRG6J3Y gVxppDTzq+BRV5tbTbrmWKu1VXJESJIN+/phPrItw+/q2UnhuXgxO0WUa9XBucu2D3ECUZOXEf8NZ pw5DSACugIbChRf5/Gul1V7DbHZnUR1WgeemI4khiDBSzRrxSPSguW5PwUEomBJb5L+VR+dhr81pB J83VDhqCxlarkYdbuzkGvTYH2j9aW4QUTVcYGw9zDjfqCodBST1lqWHPAwr84x1fQyTca3AKHW122 kAFM02+TlHYPxXfbrDfnz5alRKUzoT00F3aXe5PTeBxOd2JNCySB2rpP8vJpxD3n1fL5OjMyfqt/+ W9LZfRAw==; Received: from j130084.upc-j.chello.nl ([24.132.130.84] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1sFBgM-0000000DxXj-0Adb; Thu, 06 Jun 2024 11:53:26 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id AA11F30047C; Thu, 6 Jun 2024 13:53:25 +0200 (CEST) Date: Thu, 6 Jun 2024 13:53:25 +0200 From: Peter Zijlstra To: "Paul E. McKenney" Cc: Ankur Arora , linux-kernel@vger.kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org, rostedt@goodmis.org, mark.rutland@arm.com, juri.lelli@redhat.com, joel@joelfernandes.org, raghavendra.kt@amd.com, sshegde@linux.ibm.com, boris.ostrovsky@oracle.com, konrad.wilk@oracle.com, Ingo Molnar , Vincent Guittot Subject: Re: [PATCH v2 16/35] preempt,rcu: warn on PREEMPT_RCU=n, preempt=full Message-ID: <20240606115325.GD8774@noisy.programming.kicks-ass.net> References: <20240528003521.979836-1-ankur.a.arora@oracle.com> <20240528003521.979836-17-ankur.a.arora@oracle.com> <20240529081404.GI26599@noisy.programming.kicks-ass.net> <8734py6gvq.fsf@oracle.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: On Thu, May 30, 2024 at 04:20:26PM -0700, Paul E. McKenney wrote: > My selfish motivation here is to avoid testing this combination unless > and until someone actually has a good use for it. That doesn't make sense, the whole LAZY thing is fundamentally identical to FULL, except it sometimes delays the preemption a wee bit. But all the preemption scenarios from FULL are possible. As such, it makes far more sense to only test FULL.