From owner-freebsd-net@FreeBSD.ORG Sat Sep 7 19:56:06 2013 Return-Path: Delivered-To: freebsd-net@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 5BC55B0A; Sat, 7 Sep 2013 19:56:06 +0000 (UTC) (envelope-from ian@FreeBSD.org) Received: from mho-02-ewr.mailhop.org (mho-02-ewr.mailhop.org [204.13.248.72]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 3184A2247; Sat, 7 Sep 2013 19:56:06 +0000 (UTC) Received: from c-24-8-230-52.hsd1.co.comcast.net ([24.8.230.52] helo=damnhippie.dyndns.org) by mho-02-ewr.mailhop.org with esmtpsa (TLSv1:AES256-SHA:256) (Exim 4.72) (envelope-from ) id 1VIOc0-0008OX-Ro; Sat, 07 Sep 2013 19:56:05 +0000 Received: from [172.22.42.240] (revolution.hippie.lan [172.22.42.240]) by damnhippie.dyndns.org (8.14.3/8.14.3) with ESMTP id r87Ju2Up074842; Sat, 7 Sep 2013 13:56:02 -0600 (MDT) (envelope-from ian@FreeBSD.org) X-Mail-Handler: Dyn Standard SMTP by Dyn X-Originating-IP: 24.8.230.52 X-Report-Abuse-To: abuse@dyndns.com (see http://www.dyndns.com/services/sendlabs/outbound_abuse.html for abuse reporting information) X-MHO-User: U2FsdGVkX18bWJ+EOP5Ki+fBG9iHt6q2 Subject: Re: mbuf autotuning effect From: Ian Lepore To: hiren panchasara In-Reply-To: References: <9CBFAD35-D651-4E28-BEBB-DC3717F38567@bsdimp.com> Content-Type: text/plain; charset="us-ascii" Date: Sat, 07 Sep 2013 13:56:02 -0600 Message-ID: <1378583762.1111.512.camel@revolution.hippie.lan> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 FreeBSD GNOME Team Port Content-Transfer-Encoding: 7bit Cc: freebsd-net@FreeBSD.org, "freebsd-mips@freebsd.org" , Warner Losh 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: Sat, 07 Sep 2013 19:56:06 -0000 On Sat, 2013-09-07 at 12:21 -0700, hiren panchasara wrote: > On Sep 6, 2013 8:26 PM, "Warner Losh" wrote: > > > > > > On Sep 6, 2013, at 7:11 PM, Adrian Chadd wrote: > > > > > Yeah, why is VM_KMEM_SIZE only 12mbyte for MIPS? That's a little > low > for a > > > platform that has a direct map that's slightly larger than 12mb :) > > > > > > Warner? Juli? > > > > All architectures have it at 12MB, except sparc64 where it is 16MB. > This > can be changed with the options VM_KMEM_SIZE=xxxxx in the config file. > > Right. Does that mean for any platform, if we do not have nmbclusters > pre-set in kmeminit() than we will always have pretty low value of > vm_kmem_size. And because of that, if maxmbufmem is not pre-set (via > loader.conf) inside tunable_mbinit() , we will have very low value for > maxmbufmem too. > > I hope (partially believe) that my understanding is not entirely > correct. > Because if its correct, we arw depending on loader.conf instead of > actually > auto tuning. > I think the part of this that strikes me as strange is calling 20% of physical memory used for network buffers a "very low value". It seems outrageously high to me. I'd be pissed if that much memory got wasted on network buffers on one of our $work platforms with so little memory. So the fact that you think it's crazy-low and I think it's crazy-high may be a sign that it's auto-tuned to a reasonable compromise, and in both our cases the right fix would be to use the available knobs to tune things for our particular uses. -- Ian