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=-2.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 97AD1C19759 for ; Fri, 2 Aug 2019 00:24:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6ABB02084C for ; Fri, 2 Aug 2019 00:24:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564705488; bh=KzNocgptr3atsBh5WELd0hq9znXO426VvX/fm+IJhug=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=FhWbAoZvwQ7KYUQaM7HW8iuRmszDCTdFzXnTE34ZZ2+DTTtPu4sMYowFZBpgEJLjO 5UBqtGUXZeHBgIWbNrEP2NO4c9fB5fUQRe/D9H7mo2NQ4HsPqcM7qV0tLB1QpCFTc/ ltoIoV8fbjzjp5FTKOdJgAzJ0a9dY2r1IHJcZu6Y= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732196AbfHBAYr (ORCPT ); Thu, 1 Aug 2019 20:24:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:45812 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729359AbfHBAYr (ORCPT ); Thu, 1 Aug 2019 20:24:47 -0400 Received: from localhost (unknown [69.71.4.100]) (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 A82D6206A3; Fri, 2 Aug 2019 00:24:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1564705486; bh=KzNocgptr3atsBh5WELd0hq9znXO426VvX/fm+IJhug=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=0gfrH+8bYUaQB8OB0qSm3FlVb3htQnV+rWVUqsP+TFG8vjmBkEKezzIKpxRHIk5fn nb90R7GKv+gsx0jiSw3DQ4DbzwuTwNLJS8C/oDaFoQzpqTBa0UKoyyX2grc/OyME6r cQ2fW+8mkqBsyrZiTkQsv8c04PGCTQ0r+ARBjK/s= Date: Thu, 1 Aug 2019 19:24:42 -0500 From: Bjorn Helgaas To: Megha Dey Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, marc.zyngier@arm.com, ashok.raj@intel.com, jacob.jun.pan@linux.intel.com, megha.dey@intel.com Subject: Re: [RFC V1 RESEND 0/6] Introduce dynamic allocation/freeing of MSI-X vectors Message-ID: <20190802002442.GI151852@google.com> References: <1561162778-12669-1-git-send-email-megha.dey@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <1561162778-12669-1-git-send-email-megha.dey@linux.intel.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org Hi Megha, On Fri, Jun 21, 2019 at 05:19:32PM -0700, Megha Dey wrote: > Currently, MSI-X vector enabling and allocation for a PCIe device is > static i.e. a device driver gets only one chance to enable a specific > number of MSI-X vectors, usually during device probe. Also, in many > cases, drivers usually reserve more than required number of vectors > anticipating their use, which unnecessarily blocks resources that > could have been made available to other devices. Lastly, there is no > way for drivers to reserve more vectors, if the MSI-x has already been > enabled for that device. >   > Hence, a dynamic MSI-X kernel infrastructure can benefit drivers by > deferring MSI-X allocation to post probe phase, where actual demand > information is available. >   > This patchset enables the dynamic allocation/de-allocation of MSI-X > vectors by introducing 2 new APIs: > pci_alloc_irq_vectors_dyn() and pci_free_irq_vectors_grp(): > > We have had requests from some of the NIC/RDMA users who have lots of > interrupt resources and would like to allocate them on demand, > instead of using an all or none approach. > > The APIs are fairly well tested (multiple allocations/deallocations), > but we have no early adopters yet. Hence, sending this series as an > RFC for review and comments. > > The patches are based out of Linux 5.2-rc5. > > Megha Dey (6): > PCI/MSI: New structures/macros for dynamic MSI-X allocation > PCI/MSI: Dynamic allocation of MSI-X vectors by group > x86: Introduce the dynamic teardown function > PCI/MSI: Introduce new structure to manage MSI-x entries s/MSI-x/MSI-X/ If "entries" here means the same as "vectors" above, please use the same word. > PCI/MSI: Free MSI-X resources by group Is "resources" the same as "vectors"? > Documentation: PCI/MSI: Document dynamic MSI-X infrastructure When you post a v2 after addressing Thomas' comments, please make these subject lines imperative sentences beginning with a descriptive verb. You can run "git log --oneline drivers/pci" to see the style. If you're adding a specific interface or structure, mention it by name in the subject if it's practical. The "x86" line needs a little more context; I assume it should include "IRQ", "MSI-X", or something. > Documentation/PCI/MSI-HOWTO.txt | 38 +++++ > arch/x86/include/asm/x86_init.h | 1 + > arch/x86/kernel/x86_init.c | 6 + > drivers/pci/msi.c | 363 +++++++++++++++++++++++++++++++++++++--- > drivers/pci/probe.c | 9 + > include/linux/device.h | 3 + > include/linux/msi.h | 13 ++ > include/linux/pci.h | 61 +++++++ > kernel/irq/msi.c | 34 +++- > 9 files changed, 497 insertions(+), 31 deletions(-) > > -- > 2.7.4 >