From owner-freebsd-arm@FreeBSD.ORG Wed May 8 09:35:12 2013 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by hub.freebsd.org (Postfix) with ESMTP id BAC47229 for ; Wed, 8 May 2013 09:35:12 +0000 (UTC) (envelope-from adrian.chadd@gmail.com) Received: from mail-we0-x230.google.com (mail-we0-x230.google.com [IPv6:2a00:1450:400c:c03::230]) by mx1.freebsd.org (Postfix) with ESMTP id 581C514E for ; Wed, 8 May 2013 09:35:12 +0000 (UTC) Received: by mail-we0-f176.google.com with SMTP id p60so1506179wes.7 for ; Wed, 08 May 2013 02:35:11 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; bh=7vZuAL0xg93eOs0Zjh17Iv+lzbyXNTQwJLmWItt/q5k=; b=XSzTNUc8UCfNX153fsINp1YZQmeYvvr6bqpGOhZ7bDjuW1NVRgfM/YI6RlbMAERnLZ 1rOKpvSsSZNncrQzpA4faTkor0l1fXCywv37ZZo2xxB29N2p7kIRDqyecF3oj1vd+l5U zYZTnNWkEbbM0fQwzoLoa8djjhrb4xt1TtQIrXKWB9UaAyfceeXjLvwYb7T023vdSz7a DtKqG6TeeXNtpM8urCjGEN9u+/szks60u6qWzVeahKAUBP8IPSpmgDxweri5G9S2wcS9 NTmEAjSPOL76NiyRvRZ3Djd/U8raeRZHUE4yKGW2hyFfxRRyfdFGIEpXK+pOVi+cjYeS kqjQ== MIME-Version: 1.0 X-Received: by 10.194.248.200 with SMTP id yo8mr9174137wjc.36.1368005706932; Wed, 08 May 2013 02:35:06 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.217.58.138 with HTTP; Wed, 8 May 2013 02:35:06 -0700 (PDT) In-Reply-To: <20130508085901.GA90732@server.rulingia.com> References: <20130508085901.GA90732@server.rulingia.com> Date: Wed, 8 May 2013 02:35:06 -0700 X-Google-Sender-Auth: YAB7TnlOCcTKtkT0qjXQylDdY2s Message-ID: Subject: Re: Sawtooth ping RTT on RPi From: Adrian Chadd To: Peter Jeremy Content-Type: text/plain; charset=ISO-8859-1 Cc: freebsd-arm@freebsd.org X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Porting FreeBSD to the StrongARM Processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 08 May 2013 09:35:12 -0000 CAn you run that for a minute or two, just to capture a few cycles? Adrian On 8 May 2013 01:59, Peter Jeremy wrote: > I've noticed a sawtooth-shaped cyclic pattern in ping RTTs to my RPi > (running r249590M): > 64 bytes from 192.168.123.231: icmp_seq=22 ttl=64 time=1.321 ms > 64 bytes from 192.168.123.231: icmp_seq=23 ttl=64 time=10.312 ms > 64 bytes from 192.168.123.231: icmp_seq=24 ttl=64 time=9.328 ms > 64 bytes from 192.168.123.231: icmp_seq=25 ttl=64 time=8.335 ms > 64 bytes from 192.168.123.231: icmp_seq=26 ttl=64 time=7.411 ms > 64 bytes from 192.168.123.231: icmp_seq=27 ttl=64 time=6.448 ms > 64 bytes from 192.168.123.231: icmp_seq=28 ttl=64 time=5.497 ms > 64 bytes from 192.168.123.231: icmp_seq=29 ttl=64 time=4.508 ms > 64 bytes from 192.168.123.231: icmp_seq=30 ttl=64 time=3.540 ms > 64 bytes from 192.168.123.231: icmp_seq=31 ttl=64 time=2.588 ms > 64 bytes from 192.168.123.231: icmp_seq=32 ttl=64 time=1.635 ms > 64 bytes from 192.168.123.231: icmp_seq=33 ttl=64 time=0.738 ms > 64 bytes from 192.168.123.231: icmp_seq=34 ttl=64 time=9.770 ms > 64 bytes from 192.168.123.231: icmp_seq=35 ttl=64 time=8.805 ms > 64 bytes from 192.168.123.231: icmp_seq=36 ttl=64 time=7.833 ms > 64 bytes from 192.168.123.231: icmp_seq=37 ttl=64 time=6.843 ms > 64 bytes from 192.168.123.231: icmp_seq=38 ttl=64 time=5.869 ms > > This doesn't appear with Linux (which has a RTT of 0.42ms with > very little variance). > > What is causing the RTT pattern on FreeBSD? > Haw does Linux manage to respond so much faster? > > -- > Peter Jeremy