Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761525AbXIJUse (ORCPT ); Mon, 10 Sep 2007 16:48:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760476AbXIJUsL (ORCPT ); Mon, 10 Sep 2007 16:48:11 -0400 Received: from viefep18-int.chello.at ([213.46.255.22]:47771 "EHLO viefep32-int.chello.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1757278AbXIJUsJ (ORCPT ); Mon, 10 Sep 2007 16:48:09 -0400 Subject: Re: [RFC 0/3] Recursive reclaim (on __PF_MEMALLOC) From: Peter Zijlstra To: Christoph Lameter Cc: Daniel Phillips , linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, dkegel@google.com, David Miller , Nick Piggin In-Reply-To: References: <20070814142103.204771292@sgi.com> <200709050220.53801.phillips@phunq.net> <200709050916.04477.phillips@phunq.net> <1189454145.21778.48.camel@twins> Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=-dYdtcNtcAcP48rMZdHHn" Date: Mon, 10 Sep 2007 22:48:06 +0200 Message-Id: <1189457286.21778.68.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2945 Lines: 81 --=-dYdtcNtcAcP48rMZdHHn Content-Type: text/plain Content-Transfer-Encoding: quoted-printable On Mon, 2007-09-10 at 13:22 -0700, Christoph Lameter wrote: > On Mon, 10 Sep 2007, Peter Zijlstra wrote: >=20 > > On Mon, 2007-09-10 at 12:25 -0700, Christoph Lameter wrote: > >=20 > > > Of course boundless allocations from interrupt / reclaim context will= =20 > > > ultimately crash the system. To fix that you need to stop the network= ing=20 > > > layer from performing these. > >=20 > > Trouble is, I don't only need a network layer to not endlessly consume > > memory, I need it to 'fully' function so that we can receive the > > writeout completion. >=20 > You need to drop packets after having inspected them right? Why wont=20 > dropping packets after a certain amount of memory has been allocated work= ?=20 > What is so difficult about that? That puts the burden of tracking skb allocations and all that on the fast path. The 'simplicity' of my current approach is that we only start bean-counting (and incur the overhead thereof) once we need it. > > or > >=20 > > - have a global reserve and selectively serves sockets > > (what I've been doing) >=20 > That is a scalability problem on large systems! Global means global=20 > serialization, cacheline bouncing and possibly livelocks. If we get into=20 > this global shortage then all cpus may end up taking the same locks=20 > cycling thought the same allocation paths. Dude, breathe, these boxens of yours will never swap over network simply because you never configure swap.=20 And, _no_, it does not necessarily mean global serialisation. By simply saying there must be N pages available I say nothing about on which node they should be available, and the way the watermarks work they will be evenly distributed over the appropriate zones. > > So, if you will, you can view my approach as a reserve per socket, wher= e > > most sockets get a reserve of 0 and a few (those serving the VM) !0. >=20 > Well it looks like you know how to do it. Why not implement it? /me confused, I already have! If you talk about the IRIX model, I'm very hestitant to do that simply because that would incur the bean-counting overhead on the normal case and that will greatly upset the network people - nor would that mean that I don't need this stricter PF_MEMALLOC behaviour. --=-dYdtcNtcAcP48rMZdHHn Content-Type: application/pgp-signature; name=signature.asc Content-Description: This is a digitally signed message part -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.6 (GNU/Linux) iD8DBQBG5a2GXA2jU0ANEf4RAiMMAJ9ghHZzRhBnubU1XCju63ZZU7exDACbBiTC WYvMQoPAfvLTQiB5tAA1F3Y= =poOK -----END PGP SIGNATURE----- --=-dYdtcNtcAcP48rMZdHHn-- - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/