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=-2.4 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_MUTT autolearn=unavailable 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 48244C43613 for ; Mon, 24 Jun 2019 18:16:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1FC212089F for ; Mon, 24 Jun 2019 18:16:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=ziepe.ca header.i=@ziepe.ca header.b="glv0HRf2" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732762AbfFXSQh (ORCPT ); Mon, 24 Jun 2019 14:16:37 -0400 Received: from mail-wr1-f65.google.com ([209.85.221.65]:34667 "EHLO mail-wr1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731881AbfFXSQh (ORCPT ); Mon, 24 Jun 2019 14:16:37 -0400 Received: by mail-wr1-f65.google.com with SMTP id k11so14955857wrl.1 for ; Mon, 24 Jun 2019 11:16:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ziepe.ca; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=sJIsqOQ5eFDre2y4pDDL9/K7QpUmlmCNTD0di87N8/o=; b=glv0HRf2INHgoAzbU/KeaJR4l18uUuvmI/14yZG/YlQGVkZoefkf69d99mboSmSYJ3 kUBmB3L6FHXultbhK/4JvJG5Fc1At0jKRBNni1ZrG65adIRqsOjNaABP4HA2RPqrrhc2 vVNNd4SHFHbQJJTBSNvHIU34Cvn9PJoo9LNVbgrEEBfVdZnp3c4Bbh4CD5UlBYjP6Uwd WUft3HnKCm7fEh4o3QlUJrZ3p/cvjIZORsN9pnvYWJSlOVaEBZV4QIwwqrE9sSpFbWwq AgrKHsm2As5TJOfi2TNk7z/7mjjHrOpgpz4TRa/jfa+zOe2of3u4wRDAyHxYLZHZgkd6 aeqA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=sJIsqOQ5eFDre2y4pDDL9/K7QpUmlmCNTD0di87N8/o=; b=kPdhGsYsdoO4/VQ4mff64ua0nHpXIWGUhlN24dzG2rGRSqcmFwLUuUcQ9meLUijlpc 8gwIdgpdhyCAFjgwg3eQIj77rQcyr7yYqINfGMDtiqxefwqsVIdXoqUUSzsSrkRt4ZPb 9M4ADDLhthpvAQ+ZMmBSnUYd8v+07Mo0AA69/ISnrnvKQIyDvn/cOA5Fj2LmCAEARYSP egeJZzoUzMrUetnjvx1Taum2e6Dwcvzxlg8bCExL89KfuE67v9GK9gkDT44rp1a0i26W bVjj5GG7qCqz4hN8L053djMg3ZgChoBrVNEvW1UoPyPZmUa2ayQUH7e0P96YJZyR8gBn QyVA== X-Gm-Message-State: APjAAAUtocHqJwhubk0ya1+MYS8Q5bz7keCSKdqnm1lI9PKNprNsuPis KocIQ/EyjVxbfijqHPfQXEPBlw== X-Google-Smtp-Source: APXvYqzN+tsY00ZZUnDzGCCozz2kltRbszB8xG0KA0aMF1Z60uBAcs4mW0rG08os3rQlgEHkHPz+Hg== X-Received: by 2002:adf:ea45:: with SMTP id j5mr17926712wrn.281.1561400195211; Mon, 24 Jun 2019 11:16:35 -0700 (PDT) Received: from ziepe.ca ([66.187.232.66]) by smtp.gmail.com with ESMTPSA id j7sm16315095wru.54.2019.06.24.11.16.34 (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 24 Jun 2019 11:16:34 -0700 (PDT) Received: from jgg by jggl.ziepe.ca with local (Exim 4.90_1) (envelope-from ) id 1hfTW4-0006E8-3Z; Mon, 24 Jun 2019 15:16:32 -0300 Date: Mon, 24 Jun 2019 15:16:32 -0300 From: Jason Gunthorpe To: Logan Gunthorpe Cc: Christoph Hellwig , Dan Williams , Linux Kernel Mailing List , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, linux-rdma , Jens Axboe , Bjorn Helgaas , Sagi Grimberg , Keith Busch , Stephen Bates Subject: Re: [RFC PATCH 00/28] Removing struct page from P2PDMA Message-ID: <20190624181632.GC8268@ziepe.ca> References: <20190620161240.22738-1-logang@deltatee.com> <20190620193353.GF19891@ziepe.ca> <20190624073126.GB3954@lst.de> <20190624134641.GA8268@ziepe.ca> <20190624135024.GA11248@lst.de> <20190624135550.GB8268@ziepe.ca> <7210ba39-c923-79ca-57bb-7cf9afe21d54@deltatee.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7210ba39-c923-79ca-57bb-7cf9afe21d54@deltatee.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org On Mon, Jun 24, 2019 at 10:53:38AM -0600, Logan Gunthorpe wrote: > > It is only a very narrow case where you can take shortcuts with > > dma_addr_t, and I don't think shortcuts like are are appropriate for > > the mainline kernel.. > > I don't think it's that narrow and it opens up a lot of avenues for > system design that people are wanting to go. If your high speed data > path can avoid the root complex and CPU, you can design a system which a > much smaller CPU and fewer lanes directed at the CPU. I mean the shortcut that something generates dma_addr_t for Device A and then passes it to Device B - that is too hacky for mainline. Sounded like this series does generate the dma_addr for the correct device.. Jason