From owner-freebsd-arch@FreeBSD.ORG Sat Apr 25 17:44:17 2015 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 97889F11; Sat, 25 Apr 2015 17:44:17 +0000 (UTC) Received: from mail-ig0-x230.google.com (mail-ig0-x230.google.com [IPv6:2607:f8b0:4001:c05::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 619AA1849; Sat, 25 Apr 2015 17:44:17 +0000 (UTC) Received: by igblo3 with SMTP id lo3so36093201igb.0; Sat, 25 Apr 2015 10:44:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=xFkK/f3mDTM1zymQ6tfahXg54M8WwkSTK4vCVHK2eCA=; b=d/ujyJKGrxU70ZiaBQTIxjdY8CnefVEQKthwZD3u3a1ookR6IgJrbyCZ9VQjZfJRkS 1aeSD+MsfzA+VSQ6VanRoMvh82dwMk2CuasecjNXqXZYxR381obCM4F/WvSpGqCWWMEj Br+c0PKOFlWPU+8oKEYKy0WOiKXEP5fLESGi3mHGFQqCk7xrIdpp9UBjI2HYsuUJYeYS LiiBLn/BxzAXCZSAytWpTXuapJOWct8GtmkWIPK5cQFDryaloA3isJuaMSidHpYRRGar W3KpA01WklF9euXYwhbvEOU6l+uFQnCCUshA9YoHaiPu9QI1VWjSM1flxpE9wArmH5iX OC0A== MIME-Version: 1.0 X-Received: by 10.107.155.13 with SMTP id d13mr4820287ioe.29.1429983856820; Sat, 25 Apr 2015 10:44:16 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.36.38.133 with HTTP; Sat, 25 Apr 2015 10:44:16 -0700 (PDT) In-Reply-To: References: Date: Sat, 25 Apr 2015 10:44:16 -0700 X-Google-Sender-Auth: xit-XnkEPFT_yEq0wAFn6x8LPYc Message-ID: Subject: Re: RFC: setting performance_cx_lowest=C2 in -HEAD to avoid lock contention on many-CPU boxes From: Adrian Chadd To: "K. Macy" Cc: "freebsd-arch@freebsd.org" Content-Type: text/plain; charset=UTF-8 X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 25 Apr 2015 17:44:17 -0000 Oh the other thing, which I just mentioned to kip in IRC - all of the intel laptops I've tested (and that's a long list) don't enter CPU C7 if the power is plugged in. Ie: * power in, ACPI C2 -> CPU C6 * power in, ACPI C3 - CPU C6 * battery - ACPI C2 -> CPU C6 * battery -> ACPI C3 -> CPU C7 So having performance_cx_lowest=C3 is effectively a no-op on the devices that it'd matter on, so it's okay to just flip it to C2. -adrian