From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf0-x241.google.com (mail-lf0-x241.google.com [IPv6:2a00:1450:4010:c07::241]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 519D53B29E for ; Wed, 25 Jan 2017 16:42:19 -0500 (EST) Received: by mail-lf0-x241.google.com with SMTP id x1so22328370lff.0 for ; Wed, 25 Jan 2017 13:42:19 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=IkVwxvXrqi/NWj4VT05BW0Y8ZZmbpQLYfwOoAIcLfv4=; b=PVt/JJ/mHnQFVFowKMFbUHElM9NWS5+vbYjdKkh1CGAhXaPnib/Lc2xaDRO6FFJ5nj fOmqi4/BkTIGHIQtBNTGXCNPv24L2Z4Yd12KxwowGj6EU1/TRt7LvFst5dMWMBB2VfGB liQiyN0rHsh/NVaUTnMXNb1xjGVVkKnaC2UQSOuk5AkE7y4Set0YkOC+Wg+h5f7zW4cr MXjII6AfTNcY8ASfsCUju0haupekUWp5e47yrmNUvo5fKEDeYqf0JOAnXfbx0KzQ/Wi9 2rsUc76aQqJ7p2T2ickxCBK5fl930AhE5qD94LoOORVtMzs820dWFoGivmDftFERItGB 8PxQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=IkVwxvXrqi/NWj4VT05BW0Y8ZZmbpQLYfwOoAIcLfv4=; b=EjmKR+BdoQSeWWdh5J12wJvbopgr6krEHHN6zb4RWWyvIqcwk4L/GO+/nbwF1n1lCQ TGD8Igeu7WF3NdomMlzlxbuRI/JgxPh8aILI8bIynD78YC+K76YVPIyXWHWOdiDpIajc cgIOwZcGEGv+OuHdStSvjLCCDRR7tmnZUkQHttZVTnSJnwwl52Eh2pa4ICuDYEMdEdlY ssOommXf+ukYdZ1iOT1OYomAsUawzrxNqpCxqzKR7H3vMusCa3WEilYkxpUYJlyFbOIu oe23+qOaePz+txYMTFsuvztiwPIz5jK0exjFo/zZ2oqfOFkJvah22sGrr16YNfADwvy8 wOew== X-Gm-Message-State: AIkVDXLL00AkLlDis4j2LyBw+BVYpBdF8Eu1XqoS5WxPJOBiBDCSTRmm51xtHfswJ5broA== X-Received: by 10.46.87.73 with SMTP id r9mr16748986ljd.22.1485380538040; Wed, 25 Jan 2017 13:42:18 -0800 (PST) Received: from [192.168.100.19] (37-136-37-228.rev.dnainternet.fi. [37.136.37.228]) by smtp.gmail.com with ESMTPSA id 25sm8793694ljt.11.2017.01.25.13.42.17 (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Wed, 25 Jan 2017 13:42:17 -0800 (PST) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 9.3 \(3124\)) From: Jonathan Morton In-Reply-To: Date: Wed, 25 Jan 2017 23:42:16 +0200 Cc: bloat@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <7814778B-A328-45B4-B592-36420EE06142@gmail.com> References: <58D7E8D3-5661-4126-80D9-2F2D4E478B10@gmail.com> <908CA0EF-3D84-4EB4-ABD8-3042668E842E@gmail.com> <8B89C257-99D4-4A9A-96ED-A103A2089A46@gmail.com> To: Hans-Kristian Bakke X-Mailer: Apple Mail (2.3124) Subject: Re: [Bloat] Initial tests with BBR in kernel 4.9 X-BeenThere: bloat@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: General list for discussing Bufferbloat List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 25 Jan 2017 21:42:19 -0000 > On 25 Jan, 2017, at 23:31, Hans-Kristian Bakke = wrote: >=20 > kvm-clock is a paravirtualized clock that seems to use the CPUs TSC = capabilities if they exist. But it may not be perfect: The key capability sch_fq needs for pacing is to generate timer = interrupts at precise, sub-millisecond intervals. TSC doesn=E2=80=99t = provide that; it=E2=80=99s just a register inside the CPU which can be = read efficiently on demand. It is however possible that kvm-clock = provides that capability via the underlying HPET hardware. - Jonathan Morton