From owner-freebsd-net@FreeBSD.ORG Sun Oct 2 16:08:09 2011 Return-Path: Delivered-To: freebsd-net@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id B56BB1065678 for ; Sun, 2 Oct 2011 16:08:09 +0000 (UTC) (envelope-from jfvogel@gmail.com) Received: from mail-wy0-f182.google.com (mail-wy0-f182.google.com [74.125.82.182]) by mx1.freebsd.org (Postfix) with ESMTP id 4D10F8FC14 for ; Sun, 2 Oct 2011 16:08:08 +0000 (UTC) Received: by wyj26 with SMTP id 26so3301113wyj.13 for ; Sun, 02 Oct 2011 09:08:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=eJuqRJeuTz9oP3Rum4wJc3X957lyeulnWNeyFBApYwI=; b=a65PfProDNksCchjcPJ+i4N70FJS4zAMJsuYxiCPryEnkOxOUa0Ez5JYxpZGuyViSB I4L+RZubVZKz6meOUcrbn5F7dIjKpg1FSASgVXosziR2thShv2cH53TlGNJIm356QzAG KwT2NBFNlcHJdDB0bv85R/P8J7c/HBvWNQsQI= MIME-Version: 1.0 Received: by 10.227.42.136 with SMTP id s8mr749955wbe.28.1317571688189; Sun, 02 Oct 2011 09:08:08 -0700 (PDT) Received: by 10.180.106.35 with HTTP; Sun, 2 Oct 2011 09:08:08 -0700 (PDT) In-Reply-To: <4E886A3B.7000502@sepehrs.com> References: <4E886A3B.7000502@sepehrs.com> Date: Sun, 2 Oct 2011 09:08:08 -0700 Message-ID: From: Jack Vogel To: Hooman Fazaeli Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.5 Cc: "freebsd-net@freebsd.org" Subject: Re: em(4) high latency w/o msix X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 02 Oct 2011 16:08:09 -0000 On what hardware? Jack On Sun, Oct 2, 2011 at 6:42 AM, Hooman Fazaeli wrote: > > Latest em(4) driver from HEAD seems to have high latency > when MSIX is disabled. > > With MSIX enabled (hw.em.enable_msix=1): > > # ping -c5 192.168.1.83 > PING 192.168.1.83 (192.168.1.83): 56 data bytes > 64 bytes from 192.168.1.83: icmp_seq=0 ttl=64 time=0.055 ms > 64 bytes from 192.168.1.83: icmp_seq=1 ttl=64 time=0.076 ms > 64 bytes from 192.168.1.83: icmp_seq=2 ttl=64 time=0.066 ms > 64 bytes from 192.168.1.83: icmp_seq=3 ttl=64 time=0.051 ms > 64 bytes from 192.168.1.83: icmp_seq=4 ttl=64 time=0.063 ms > > --- 192.168.1.83 ping statistics --- > 5 packets transmitted, 5 packets received, 0.0% packet loss > round-trip min/avg/max/stddev = 0.051/0.062/0.076/0.009 ms > > With MSIX disabled: > > # ping -c5 192.168.1.83 > PING 192.168.1.83 (192.168.1.83): 56 data bytes > 64 bytes from 192.168.1.83: icmp_seq=0 ttl=64 time=0.180 ms > 64 bytes from 192.168.1.83: icmp_seq=1 ttl=64 time=0.164 ms > 64 bytes from 192.168.1.83: icmp_seq=2 ttl=64 time=0.169 ms > 64 bytes from 192.168.1.83: icmp_seq=3 ttl=64 time=0.172 ms > 64 bytes from 192.168.1.83: icmp_seq=4 ttl=64 time=0.167 ms > > --- 192.168.1.83 ping statistics --- > 5 packets transmitted, 5 packets received, 0.0% packet loss > round-trip min/avg/max/stddev = 0.164/0.170/0.180/0.005 ms > > As you see, w/o MSIX, RTT increases by a factor of 3. > > I also tested the following drivers: > - igb(4) from HEAD: OK. > - Stock 7.3-RELEASE: OK. > - Stock 7.4-RELEASE: problem exist. > > Any ideas? > > > > >