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=-1.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,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 52853C433E2 for ; Mon, 1 Jun 2020 17:41:11 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (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 2B3602073B for ; Mon, 1 Jun 2020 17:41:11 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="aAWp9FZ4"; 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 2B3602073B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Message-ID: Subject:To:From:Date:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:References: List-Owner; bh=HcBXNJIDbfnZ5UCLRxmwiaxMM3128zfAiHrKrSF5OTw=; b=aAWp9FZ46RZ0SJ ItYTISNxgKa3GTPLUcHeYW111JWG0TA5JdMWmMc5ZTOwI042H/mdPchnDPf6SSOgHAeF/dlER53Cb cG1cgR1ted6naQIjJIgBmyYwrAdM5Wr+L6sM+gLjD9A+3dbRMb9C6U6ma0eKdTjThL2vMque3esir VGDEk9TC98bjLuD58jJuzJ2Kz2clG9GaqOkM4AXW3QwNxUyDbpvs2Wg71zjKIJKRvwTi4FQiSuwD4 FCfiRHJUane3TBUKL7DJDoZcK7KpPNkeAi33dSGbq5IxBDNKtEBaFHMFXw3XkfNBJBumFswx4zKUt 6NULMbsni5hIuvaZjUSw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1jfoQw-0003FF-MD; Mon, 01 Jun 2020 17:41:10 +0000 Received: from mail.kernel.org ([198.145.29.99]) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1jfoQt-0003Er-L3 for linux-arm-kernel@lists.infradead.org; Mon, 01 Jun 2020 17:41:09 +0000 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> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200601_104107_710771_3EFC49A1 X-CRM114-Status: GOOD ( 15.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: jean-philippe , Lorenzo Pieralisi , 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, Wangzhou , linux-crypto@vger.kernel.org, Sudeep Holla , Bjorn Helgaas , Zhangfei Gao , linux-arm-kernel@lists.infradead.org, Len Brown Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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/ _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel