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=-0.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C62F6C433E1 for ; Mon, 1 Jun 2020 17:41:09 +0000 (UTC) Received: from hemlock.osuosl.org (smtp2.osuosl.org [140.211.166.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6B6C120734 for ; Mon, 1 Jun 2020 17:41:09 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="PBS/XvI5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6B6C120734 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from localhost (localhost [127.0.0.1]) by hemlock.osuosl.org (Postfix) with ESMTP id 2FFD287DF3; Mon, 1 Jun 2020 17:41:09 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from hemlock.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id ftr5B8OQhAEo; Mon, 1 Jun 2020 17:41:08 +0000 (UTC) Received: from lists.linuxfoundation.org (lf-lists.osuosl.org [140.211.9.56]) by hemlock.osuosl.org (Postfix) with ESMTP id ADCEF87D8B; Mon, 1 Jun 2020 17:41:08 +0000 (UTC) Received: from lf-lists.osuosl.org (localhost [127.0.0.1]) by lists.linuxfoundation.org (Postfix) with ESMTP id 9F019C088C; Mon, 1 Jun 2020 17:41:08 +0000 (UTC) Received: from whitealder.osuosl.org (smtp1.osuosl.org [140.211.166.138]) by lists.linuxfoundation.org (Postfix) with ESMTP id 66E04C0176 for ; Mon, 1 Jun 2020 17:41:07 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by whitealder.osuosl.org (Postfix) with ESMTP id 50C8B86439 for ; Mon, 1 Jun 2020 17:41:07 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from whitealder.osuosl.org ([127.0.0.1]) by localhost (.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 9RHyn+jmOaXE for ; Mon, 1 Jun 2020 17:41:06 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.7.6 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by whitealder.osuosl.org (Postfix) with ESMTPS id D9DE686429 for ; Mon, 1 Jun 2020 17:41:06 +0000 (UTC) Received: from localhost (mobile-166-175-190-200.mycingular.net [166.175.190.200]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 48FEF206A4; Mon, 1 Jun 2020 17:41:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591033266; bh=egFH6RgQ4a+4kLCfGrEDkjv5v4bJblqDQOjodPikqEM=; h=Date:From:To:Cc:Subject:In-Reply-To:From; b=PBS/XvI5mPBJhMQPW3QR/267YghZh8VBNHFVIA3y76nvmv7wSAOnIG8ZofBmrwL3W hjX/e/kbh6hI/0SHMT/KsCJ3IYwK/78zwY6ZY8W6ZDDtNYI4kfbVVgq5NF84Mj/Dz5 u9OiYWmcq6uvLgae6Udy20G6q8HsslAkBraLQcZo= Date: Mon, 1 Jun 2020 12:41:04 -0500 From: Bjorn Helgaas To: Joerg Roedel Subject: Re: [PATCH 0/2] Introduce PCI_FIXUP_IOMMU Message-ID: <20200601174104.GA734973@bjorn-Precision-5520> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20200528073344.GO5221@8bytes.org> Cc: jean-philippe , Herbert Xu , Arnd Bergmann , linux-pci@vger.kernel.org, Greg Kroah-Hartman , Hanjun Guo , "Rafael J. Wysocki" , linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, kenneth-lee-2012@foxmail.com, linux-acpi@vger.kernel.org, linux-crypto@vger.kernel.org, Sudeep Holla , Bjorn Helgaas , Zhangfei Gao , linux-arm-kernel@lists.infradead.org, Len Brown X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: iommu-bounces@lists.linux-foundation.org Sender: "iommu" On Thu, May 28, 2020 at 09:33:44AM +0200, Joerg Roedel wrote: > On Wed, May 27, 2020 at 01:18:42PM -0500, Bjorn Helgaas wrote: > > Is this slowdown significant? We already iterate over every device > > when applying PCI_FIXUP_FINAL quirks, so if we used the existing > > PCI_FIXUP_FINAL, we wouldn't be adding a new loop. We would only be > > adding two more iterations to the loop in pci_do_fixups() that tries > > to match quirks against the current device. I doubt that would be a > > measurable slowdown. > > I don't know how significant it is, but I remember people complaining > about adding new PCI quirks because it takes too long for them to run > them all. That was in the discussion about the quirk disabling ATS on > AMD Stoney systems. > > So it probably depends on how many PCI devices are in the system whether > it causes any measureable slowdown. I found this [1] from Paul Menzel, which was a slowdown caused by quirk_usb_early_handoff(). I think the real problem is individual quirks that take a long time. The PCI_FIXUP_IOMMU things we're talking about should be fast, and of course, they're only run for matching devices anyway. So I'd rather keep them as PCI_FIXUP_FINAL than add a whole new phase. Bjorn [1] https://lore.kernel.org/linux-pci/b1533fd5-1fae-7256-9597-36d3d5de9d2a@molgen.mpg.de/ _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu