From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AD908C433E0 for ; Sat, 27 Jun 2020 07:03:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 92A7D20857 for ; Sat, 27 Jun 2020 07:03:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726056AbgF0HCj (ORCPT ); Sat, 27 Jun 2020 03:02:39 -0400 Received: from verein.lst.de ([213.95.11.211]:53802 "EHLO verein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725926AbgF0HCj (ORCPT ); Sat, 27 Jun 2020 03:02:39 -0400 Received: by verein.lst.de (Postfix, from userid 2407) id 9E9AF68B02; Sat, 27 Jun 2020 09:02:36 +0200 (CEST) Date: Sat, 27 Jun 2020 09:02:36 +0200 From: Christoph Hellwig To: Jonathan Lemon Cc: Christoph Hellwig , =?iso-8859-1?Q?Bj=F6rn_T=F6pel?= , Alexander Duyck , netdev@vger.kernel.org, iommu@lists.linux-foundation.org Subject: Re: the XSK buffer pool needs be to reverted Message-ID: <20200627070236.GA11854@lst.de> References: <20200626074725.GA21790@lst.de> <20200626205412.xfe4lywdbmh3kmri@bsd-mbp> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200626205412.xfe4lywdbmh3kmri@bsd-mbp> User-Agent: Mutt/1.5.17 (2007-11-01) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jun 26, 2020 at 01:54:12PM -0700, Jonathan Lemon wrote: > On Fri, Jun 26, 2020 at 09:47:25AM +0200, Christoph Hellwig wrote: > > > > Note that this is somewhat urgent, as various of the APIs that the code > > is abusing are slated to go away for Linux 5.9, so this addition comes > > at a really bad time. > > Could you elaborate on what is upcoming here? Moving all these calls out of line, and adding a bypass flag to avoid the indirect function call for IOMMUs in direct mapped mode. > Also, on a semi-related note, are there limitations on how many pages > can be left mapped by the iommu? Some of the page pool work involves > leaving the pages mapped instead of constantly mapping/unmapping them. There are, but I think for all modern IOMMUs they are so big that they don't matter. Maintaines of the individual IOMMU drivers might know more. > On a heavily loaded box with iommu enabled, it seems that quite often > there is contention on the iova_lock. Are there known issues in this > area? I'll have to defer to the IOMMU maintainers, and for that you'll need to say what code you are using. Current mainlaine doesn't even have an iova_lock anywhere.