From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx1.redhat.com (mx1.redhat.com [209.132.183.28]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id EB1B23B29E for ; Wed, 11 Oct 2017 17:31:03 -0400 (EDT) Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1FCF7C04B303; Wed, 11 Oct 2017 21:31:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com 1FCF7C04B303 Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=brouer@redhat.com Received: from localhost (ovpn-200-23.brq.redhat.com [10.40.200.23]) by smtp.corp.redhat.com (Postfix) with ESMTP id 9015860BED; Wed, 11 Oct 2017 21:30:58 +0000 (UTC) Date: Wed, 11 Oct 2017 23:30:56 +0200 From: Jesper Dangaard Brouer To: Bob McMahon Cc: David Reed , make-wifi-fast@lists.bufferbloat.net, Johannes Berg , brouer@redhat.com Message-ID: <20171011233056.3634daea@redhat.com> In-Reply-To: References: <1507581711.45638427@apps.rackspace.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 11 Oct 2017 21:31:03 +0000 (UTC) Subject: Re: [Make-wifi-fast] less latency, more filling... for wifi X-BeenThere: make-wifi-fast@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 11 Oct 2017 21:31:04 -0000 Hi Bob, Just wanted to let you know, that after you posted this, I've started to use your iperf2 tool again. To verify some of my kernel code. I particularly liked that I can send with a specific PPS rate, like: iperf2-git -c 172.16.0.2 -e -u -b 20000pps -i 1 On Mon, 9 Oct 2017 14:04:35 -0700 Bob McMahon wrote: > Not sure if this is helpful but we've added end/end latency measurements > for UDP traffic in iperf 2.0.10 . I tried it out, but the clock between my two machines are not accurate enough (as you hint below). > It does require the clocks to be synched. I use a spectracom tsync pcie > card with either an oven controlled oscillator or a GPS disciplined one, > then use precision time protocol to distribute the clock over ip > multicast. > For Linux, the traffic threads are set to realtime scheduling > to minimize latency adds per thread scheduling.. If I use the --realtime option, I did run into issues where the server thread would busypoll 100% after e.g. a client stopped a test prematurely. And I had to kill it with -9. Thanks for you work! -- Best regards, Jesper Dangaard Brouer MSc.CS, Principal Kernel Engineer at Red Hat LinkedIn: http://www.linkedin.com/in/brouer