From owner-freebsd-net@FreeBSD.ORG Tue Apr 16 12:24:51 2013 Return-Path: Delivered-To: freebsd-net@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 AA62E3FB; Tue, 16 Apr 2013 12:24:51 +0000 (UTC) (envelope-from sepherosa@gmail.com) Received: from mail-la0-x236.google.com (mail-la0-x236.google.com [IPv6:2a00:1450:4010:c03::236]) by mx1.freebsd.org (Postfix) with ESMTP id D6F6C852; Tue, 16 Apr 2013 12:24:50 +0000 (UTC) Received: by mail-la0-f54.google.com with SMTP id ec20so394403lab.41 for ; Tue, 16 Apr 2013 05:24:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:x-received:in-reply-to:references:date:message-id :subject:from:to:cc:content-type; bh=lyI7vLMTrvZUWKWbYf3fVIwchqtYNzCJkNmW50okx28=; b=uiBRfGTOyaSHcJK8adHyiQndJlVRLqw1NTbegnJDRZrEuizadT85p1yIUmIRff1KDW r0YE5BNqaJy0M+uBrASaSI+ypJwoQl03hz+3GqQENYwIzvsP0ZA80LlkCN/rTXgJPsCZ bTv1jvOMtygCvVU+zhiwqOMTgN3+MvaKhyWhuG4h4kEx3RM0diZgGv7tOym7ZagpsUog RmsJkuu5YZrgwmP/4zQAbaT1GQqLvGG20gOzMlpcXxhAwJm3ik+oZCnOWvFYLAoYdqX7 eafyDMGT3u3OQpQx2wnULJFstN8zgr77p+AouhcHb0IDwHha9JcsdkzejxTXQgRt8nwO r/ig== MIME-Version: 1.0 X-Received: by 10.112.76.39 with SMTP id h7mr1235278lbw.118.1366115089806; Tue, 16 Apr 2013 05:24:49 -0700 (PDT) Received: by 10.114.58.179 with HTTP; Tue, 16 Apr 2013 05:24:49 -0700 (PDT) In-Reply-To: <20130416152121.G904@besplex.bde.org> References: <1365781568.1418.1.camel@localhost> <20130413200512.G1165@besplex.bde.org> <1366065356.1350.7.camel@localhost> <20130416152121.G904@besplex.bde.org> Date: Tue, 16 Apr 2013 20:24:49 +0800 Message-ID: Subject: Re: bge(4) sysctl tuneables -- a blast from the past. From: Sepherosa Ziehau To: Bruce Evans Content-Type: text/plain; charset=ISO-8859-1 Cc: "pyunyh@gmail.com" , "freebsd-net@freebsd.org" , David Christensen , bde X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 16 Apr 2013 12:24:51 -0000 On Tue, Apr 16, 2013 at 1:56 PM, Bruce Evans wrote: > > Technical bugs include: > - wrong defaults are claimed for *coal_ticks. The defaults are 150, but > are claimed to be 150 milliseconds. These values are dimensionless, > but since ticks take 1 microsecond each, 150 gives 150 microseconds, > not 150 milliseconds. The real effect of TX coalesce ticks is confusing to me; TX interrupt does not come at the rate you have specified, at least for several PCI-e bge(4) I have tested. However, RX coalesce ticks work as expected. Here is how the tests were conducted: - Send only test, no RX - Each packet consume only one BD; UDP datagram, using hardware checksum offloading - TX coalesce BDs is set to 0, so only TX coalesce ticks have effect The interrupt rate I had got seemed to be related to packet size?! I had tested two TX coalesce ticks settings: (the result I had recorded was using BCM5720) The first setting was 1023us; the first col is UDP data size, the second col is rough interrupt rate 18B 667/s 64B 611/s 128B 538/s 256B 432/s 512B 311/s 1024B 194/s 1472B 146/s Tecond setting was 128us; the first col is UDP data size, the second col is rough interrupt rate 18B 1647/s 64B 1338/s 128B 1030/s 256B 700/s 512B 430/s 1024B 235/s 1472B 169/s Well, to be frank, it does not make too much sense to me. I also twisted the HCC_MODE CLRTICK_TX a bit, but didn't get determined result. (davidch is CC'd) Best Regards, sephe -- Tomorrow Will Never Die