From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sun, 20 May 2001 09:41:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sun, 20 May 2001 09:41:32 -0400 Received: from penguin.e-mind.com ([195.223.140.120]:14456 "EHLO penguin.e-mind.com") by vger.kernel.org with ESMTP id ; Sun, 20 May 2001 09:41:26 -0400 Date: Sun, 20 May 2001 15:40:44 +0200 From: Andrea Arcangeli To: Ivan Kokshaysky Cc: Richard Henderson , linux-kernel@vger.kernel.org Subject: Re: alpha iommu fixes Message-ID: <20010520154044.C18119@athlon.random> In-Reply-To: <20010518214617.A701@jurassic.park.msu.ru> <20010519155502.A16482@athlon.random> <20010519231131.A2840@jurassic.park.msu.ru> <20010520044013.A18119@athlon.random> <20010520161234.B8223@jurassic.park.msu.ru> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20010520161234.B8223@jurassic.park.msu.ru>; from ink@jurassic.park.msu.ru on Sun, May 20, 2001 at 04:12:34PM +0400 X-GnuPG-Key-URL: http://e-mind.com/~andrea/aa.gnupg.asc X-PGP-Key-URL: http://e-mind.com/~andrea/aa.asc Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, May 20, 2001 at 04:12:34PM +0400, Ivan Kokshaysky wrote: > On Sun, May 20, 2001 at 04:40:13AM +0200, Andrea Arcangeli wrote: > > I was only talking about when you get the "pci_map_sg failed" because > > you have not 3 but 300 scsi disks connected to your system and you are > > writing to all them at the same time allocating zillons of pte, and one > > of your drivers (possibly not even a storage driver) is actually not > > checking the reval of the pci_map_* functions. You don't need a pte > > memleak to trigger it, even regardless of the fact I grown the dynamic > > window to 1G which makes it 8 times harder to trigger than in mainline. > > I think you're too pessimistic. Don't mix "disks" and "controllers" -- I'm not pessimistic, I'm fairly relaxed also with a 512Mbyte dynamic window (that's why I did the change in first place) and I agree that it should take care of hiding all those bugs on 99% of hardware configurations, but OTOH I don't want things to work by luck and I'd prefer if the real bugs gets fixed as well eventually. > SCSI adapter with 10 drives attached is a single DMA agent, not 10 agents. you can do simultaneous I/O to all the disks, so you will keep those dma entries for the SG for each disk in-use at the same time. > If you're so concerned about Big Iron, go ahead and implement 64-bit PCI > support, it would be right long-term solution. I'm pretty sure that > high-end servers use mostly this kind of hardware. Certainly 64bit pci is supported but that doesn't change the fact you can as well have 32bit devices on those boxes. > Oh, well. This doesn't mean that I'm disagreed with what you said. :-) > Driver writers must realize that pci mappings are limited resources. Exactly. Andrea