From owner-freebsd-net@freebsd.org  Wed Apr 20 18:23:25 2016
Return-Path: <owner-freebsd-net@freebsd.org>
Delivered-To: freebsd-net@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id EB653B15AA0
 for <freebsd-net@mailman.ysv.freebsd.org>;
 Wed, 20 Apr 2016 18:23:25 +0000 (UTC)
 (envelope-from mad@madpilot.net)
Received: from mail.madpilot.net (grunt.madpilot.net [78.47.145.38])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client did not present a certificate)
 by mx1.freebsd.org (Postfix) with ESMTPS id AE23B1293
 for <freebsd-net@freebsd.org>; Wed, 20 Apr 2016 18:23:24 +0000 (UTC)
 (envelope-from mad@madpilot.net)
Received: from mail (mail [192.168.254.3])
 by mail.madpilot.net (Postfix) with ESMTP id 3qqqxv5D2CzZqp;
 Wed, 20 Apr 2016 20:23:15 +0200 (CEST)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=madpilot.net; h=
 content-transfer-encoding:content-type:content-type:in-reply-to
 :mime-version:user-agent:date:date:message-id:from:from
 :references:subject:subject:received:received; s=mail; t=
 1461176594; x=1462990995; bh=UuwvSas8C4/XfS4Hu9dF55ijFHcNuu2mfxt
 tcppaWgo=; b=hcXnXjF+SU6oi4U47k68JrRE8oZzLGPTnv/NmsAA1SSCam+hHDF
 D4NqplCovo+qHtkBkw86dbK8gnnj53trtxAOzDHiaQGieOc1AKKlCqjmNEdZ3Qc4
 f5GwMKk64WppAno0gGiBsyqHCwvBejQl+GaE9Me3dJzYL/Q5wXo6zpmk=
Received: from mail.madpilot.net ([192.168.254.3])
 by mail (mail.madpilot.net [192.168.254.3]) (amavisd-new, port 10024)
 with ESMTP id YcmVrl71-QtD; Wed, 20 Apr 2016 20:23:14 +0200 (CEST)
Received: from tommy.madpilot.net (micro.madpilot.net [88.149.173.206])
 by mail.madpilot.net (Postfix) with ESMTPSA;
 Wed, 20 Apr 2016 20:23:14 +0200 (CEST)
Subject: Re: HZ kernel configuration still needed nowadays?
To: Raimundo Santos <raitech@gmail.com>,
 "freebsd-net@freebsd.org" <freebsd-net@freebsd.org>
References: <CAGQ6iC9=fYmidPGOtScxvH+ydz5vjBxkHEZdf6uHOb-aXguzgw@mail.gmail.com>
From: Guido Falsi <mad@madpilot.net>
Message-ID: <9c618d17-c9da-5952-86a6-90b54e2e0d5c@madpilot.net>
Date: Wed, 20 Apr 2016 20:23:13 +0200
User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:45.0) Gecko/20100101
 Thunderbird/45.0
MIME-Version: 1.0
In-Reply-To: <CAGQ6iC9=fYmidPGOtScxvH+ydz5vjBxkHEZdf6uHOb-aXguzgw@mail.gmail.com>
Content-Type: text/plain; charset=windows-1252
Content-Transfer-Encoding: 7bit
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.21
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net/>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/freebsd-net>,
 <mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 20 Apr 2016 18:23:26 -0000

On 04/20/16 18:54, Raimundo Santos wrote:
> Hello, folks!
> 
> I have a FreeBSD 10.2-RELEASE taking care of the bandwidth limitation of a
> small WISP. There are around 1400 dynamic queues and dynamic schedulers,
> and a big queue for a better QoS.
> 
> Every scheduler and the big one for QoS have GRED configured.
> 
> In this scenario, it's needed to compile my kernel with HZ=1000?

AFAIK HZ=1000 has been the default since 6.0.

The only tuning suggestion relative to HZ its to lower it on less
powerful systems where such granularity isn't needed.

BTW HZ setting can be done in loader.conf at boot time, no need for
recompilation.

> 
> And, in general, is it still needed to compile a custom kernel for dummynet
> to work more precisely?

I think at present it can work fine with the HZ=1000 default. To know if
that's ok for your workload can only be verified with testing.


-- 
Guido Falsi <mad@madpilot.net>