From owner-freebsd-arch@FreeBSD.ORG Tue Nov 25 02:06:11 2008 Return-Path: Delivered-To: arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id E6E041065670 for ; Tue, 25 Nov 2008 02:06:11 +0000 (UTC) (envelope-from jroberson@jroberson.net) Received: from wa-out-1112.google.com (wa-out-1112.google.com [209.85.146.177]) by mx1.freebsd.org (Postfix) with ESMTP id C59078FC13 for ; Tue, 25 Nov 2008 02:06:11 +0000 (UTC) (envelope-from jroberson@jroberson.net) Received: by wa-out-1112.google.com with SMTP id m34so1172744wag.27 for ; Mon, 24 Nov 2008 18:06:11 -0800 (PST) Received: by 10.114.195.19 with SMTP id s19mr2357596waf.10.1227578771499; Mon, 24 Nov 2008 18:06:11 -0800 (PST) Received: from ?10.0.1.199? (cpe-66-91-191-118.hawaii.res.rr.com [66.91.191.118]) by mx.google.com with ESMTPS id n20sm4588315pof.10.2008.11.24.18.06.08 (version=SSLv3 cipher=RC4-MD5); Mon, 24 Nov 2008 18:06:10 -0800 (PST) Date: Mon, 24 Nov 2008 16:03:35 -1000 (HST) From: Jeff Roberson X-X-Sender: jroberson@desktop To: gnn@freebsd.org In-Reply-To: Message-ID: <20081124160316.I971@desktop> References: <20081123213232.A971@desktop> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: arch@freebsd.org Subject: Re: Limiting mbuf memory. X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 25 Nov 2008 02:06:12 -0000 On Mon, 24 Nov 2008, gnn@freebsd.org wrote: > At Sun, 23 Nov 2008 21:46:08 -1000 (HST), > Jeff Roberson wrote: >> >> I'm developing a patch for an alternate memory layout for mbuf clusters >> that relies on contigmalloc. Since this can fail, we'll still have to >> retain the capability of allocating traditional clusters. I'll report >> details on that later. I'm writing this email to address the issue of >> resource accounting in mbufs. >> >> Presently we use a set of limits on individual zones or sizes of mbufs. >> Standard mbufs, clusters, page size jumbos, 9k jumbos, and 16k jumbos. >> Each is administered sperately. I think this is getting a bit unwieldy. >> In the future, we may have even more sizes. This also introduces problems >> because I will have two cluster zones do they each get their own limit? >> >> I would like to consolidate this into a single limit on the number of >> pages in total allocated to networking. With perhaps some fractional >> reservation for standard mbufs and clusters to make sure they aren't >> overwhelmed by the larger buffers. >> >> This would be implemented by overriding the uma zone page allocator for >> each of the mbuf zones with one that counts pages for all. Should we >> reach the limit we'll block depending on the wait settings of the >> requestor. The limit and sleep will probably be protected by a global >> lock which won't be an issue because trips to the back end allocator are >> infrequent and protected by their own global lock anyhow. >> >> How do people feel about this? To be clear this would eliminate: >> >> nmbclusters, nmbjumbop, nmbjumbo9, nmbjumbo16 and related config settings >> and sysctls. They would be replaced by something like 'maxmbufbytes'. >> Presently we place no limit on small mbufs. I could go either way on >> this. It could be added to the limit or not. >> > > I think this is a good idea with the caveat that I prefer the idea in > paragraph 3 about reserving a bit of head room so we don't deadlock. > A very common bug in the past was to run out of mbufs when using a lot > of small UDP packets. Ok, I believe the existing per-type limits will facilitate this. Thanks, Jeff > > Best, > George >