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=-15.9 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 2BC63C48BDF for ; Wed, 16 Jun 2021 00:40:37 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16B46613CD for ; Wed, 16 Jun 2021 00:40:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231821AbhFPAml (ORCPT ); Tue, 15 Jun 2021 20:42:41 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:38923 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231791AbhFPAmk (ORCPT ); Tue, 15 Jun 2021 20:42:40 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1623804034; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=327NKSVoyLXkfvSgIC6wSAcEEzB6rOENlygol386mU8=; b=H1AXN8Na7VFbz6T/oxHoThve5uNLxrQbvKg5o8fuKIbLQ4I+cOBVDMgIH5X7ZLgH3mlJQV tIvOlTglEf6KyKwDob54SMuHcipS6myh7lsWOsgYL+rgcbP8KR666dh7pXkAqqsHv/HLit eYDTqTm1HEFRvkgBhW2XTkERIQtqt80= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-70-8DNMEgDgOeeiz8UMqMeYGQ-1; Tue, 15 Jun 2021 20:40:30 -0400 X-MC-Unique: 8DNMEgDgOeeiz8UMqMeYGQ-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id AF3F71084F41; Wed, 16 Jun 2021 00:40:28 +0000 (UTC) Received: from T590 (ovpn-12-78.pek2.redhat.com [10.72.12.78]) by smtp.corp.redhat.com (Postfix) with ESMTPS id AAA76620DE; Wed, 16 Jun 2021 00:40:18 +0000 (UTC) Date: Wed, 16 Jun 2021 08:40:14 +0800 From: Ming Lei To: Bjorn Helgaas Cc: Thomas Gleixner , LKML , Christoph Hellwig , Jens Axboe , linux-block@vger.kernel.org, Sagi Grimberg , linux-nvme@lists.infradead.org, linux-pci@vger.kernel.org, Keith Busch , Marc Zyngier , Sumit Saxena , Kashyap Desai , Shivasharan Srikanteshwara Subject: Re: [patch v6 3/7] genirq/affinity: Add new callback for (re)calculating interrupt sets Message-ID: References: <20190216172228.512444498@linutronix.de> <20210615195707.GA2909907@bjorn-Precision-5520> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210615195707.GA2909907@bjorn-Precision-5520> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Tue, Jun 15, 2021 at 02:57:07PM -0500, Bjorn Helgaas wrote: > On Sat, Feb 16, 2019 at 06:13:09PM +0100, Thomas Gleixner wrote: > > From: Ming Lei > > > > The interrupt affinity spreading mechanism supports to spread out > > affinities for one or more interrupt sets. A interrupt set contains one or > > more interrupts. Each set is mapped to a specific functionality of a > > device, e.g. general I/O queues and read I/O queus of multiqueue block > > devices. > > > > The number of interrupts per set is defined by the driver. It depends on > > the total number of available interrupts for the device, which is > > determined by the PCI capabilites and the availability of underlying CPU > > resources, and the number of queues which the device provides and the > > driver wants to instantiate. > > > > The driver passes initial configuration for the interrupt allocation via a > > pointer to struct irq_affinity. > > > > Right now the allocation mechanism is complex as it requires to have a loop > > in the driver to determine the maximum number of interrupts which are > > provided by the PCI capabilities and the underlying CPU resources. This > > loop would have to be replicated in every driver which wants to utilize > > this mechanism. That's unwanted code duplication and error prone. > > > > In order to move this into generic facilities it is required to have a > > mechanism, which allows the recalculation of the interrupt sets and their > > size, in the core code. As the core code does not have any knowledge about the > > underlying device, a driver specific callback is required in struct > > irq_affinity, which can be invoked by the core code. The callback gets the > > number of available interupts as an argument, so the driver can calculate the > > corresponding number and size of interrupt sets. > > > > At the moment the struct irq_affinity pointer which is handed in from the > > driver and passed through to several core functions is marked 'const', but for > > the callback to be able to modify the data in the struct it's required to > > remove the 'const' qualifier. > > > > Add the optional callback to struct irq_affinity, which allows drivers to > > recalculate the number and size of interrupt sets and remove the 'const' > > qualifier. > > > > For simple invocations, which do not supply a callback, a default callback > > is installed, which just sets nr_sets to 1 and transfers the number of > > spreadable vectors to the set_size array at index 0. > > > > This is for now guarded by a check for nr_sets != 0 to keep the NVME driver > > working until it is converted to the callback mechanism. > > > > To make sure that the driver configuration is correct under all circumstances > > the callback is invoked even when there are no interrupts for queues left, > > i.e. the pre/post requirements already exhaust the numner of available > > interrupts. > > > > At the PCI layer irq_create_affinity_masks() has to be invoked even for the > > case where the legacy interrupt is used. That ensures that the callback is > > invoked and the device driver can adjust to that situation. > > > > [ tglx: Fixed the simple case (no sets required). Moved the sanity check > > for nr_sets after the invocation of the callback so it catches > > broken drivers. Fixed the kernel doc comments for struct > > irq_affinity and de-'This patch'-ed the changelog ] > > > > Signed-off-by: Ming Lei > > Signed-off-by: Thomas Gleixner > > > @@ -1196,6 +1196,13 @@ int pci_alloc_irq_vectors_affinity(struc > > /* use legacy irq if allowed */ > > if (flags & PCI_IRQ_LEGACY) { > > if (min_vecs == 1 && dev->irq) { > > + /* > > + * Invoke the affinity spreading logic to ensure that > > + * the device driver can adjust queue configuration > > + * for the single interrupt case. > > + */ > > + if (affd) > > + irq_create_affinity_masks(1, affd); > > This looks like a leak because irq_create_affinity_masks() returns a > pointer to kcalloc()ed space, but we throw away the pointer. > > Or is there something very subtle going on here, like this special > case doesn't allocate anything? I do see the "Nothing to assign?" > case that returns NULL with no alloc, but it's not completely trivial > to verify that we take that case here. The purpose is to provide chance to call ->calc_sets() for single interrupt, maybe it can be improved by the following change: diff --git a/drivers/pci/msi.c b/drivers/pci/msi.c index 217dc9f0231f..025c647279f5 100644 --- a/drivers/pci/msi.c +++ b/drivers/pci/msi.c @@ -1223,8 +1223,7 @@ int pci_alloc_irq_vectors_affinity(struct pci_dev *dev, unsigned int min_vecs, * the device driver can adjust queue configuration * for the single interrupt case. */ - if (affd) - irq_create_affinity_masks(1, affd); + irq_affinity_calc_sets_legacy(affd); pci_intx(dev, 1); return 1; } diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h index 4777850a6dc7..f21f93ce460b 100644 --- a/include/linux/interrupt.h +++ b/include/linux/interrupt.h @@ -368,6 +368,7 @@ irq_create_affinity_masks(unsigned int nvec, struct irq_affinity *affd); unsigned int irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec, const struct irq_affinity *affd); +void irq_affinity_calc_sets_legacy(struct irq_affinity *affd); #else /* CONFIG_SMP */ @@ -419,6 +420,10 @@ irq_calc_affinity_vectors(unsigned int minvec, unsigned int maxvec, return maxvec; } +static inline void irq_affinity_calc_sets_legacy(struct irq_affinity *affd) +{ +} + #endif /* CONFIG_SMP */ /* diff --git a/kernel/irq/affinity.c b/kernel/irq/affinity.c index 4d89ad4fae3b..d01f7dfa5712 100644 --- a/kernel/irq/affinity.c +++ b/kernel/irq/affinity.c @@ -405,6 +405,30 @@ static void default_calc_sets(struct irq_affinity *affd, unsigned int affvecs) affd->set_size[0] = affvecs; } +static void irq_affinity_calc_sets(unsigned int affvecs, + struct irq_affinity *affd) +{ + /* + * Simple invocations do not provide a calc_sets() callback. Install + * the generic one. + */ + if (!affd->calc_sets) + affd->calc_sets = default_calc_sets; + + /* Recalculate the sets */ + affd->calc_sets(affd, affvecs); + + WARN_ON_ONCE(affd->nr_sets > IRQ_AFFINITY_MAX_SETS); +} + +/* Provide a chance to call ->calc_sets for legacy */ +void irq_affinity_calc_sets_legacy(struct irq_affinity *affd) +{ + if (!affd) + return; + irq_affinity_calc_sets(0, affd); +} + /** * irq_create_affinity_masks - Create affinity masks for multiqueue spreading * @nvecs: The total number of vectors @@ -429,17 +453,8 @@ irq_create_affinity_masks(unsigned int nvecs, struct irq_affinity *affd) else affvecs = 0; - /* - * Simple invocations do not provide a calc_sets() callback. Install - * the generic one. - */ - if (!affd->calc_sets) - affd->calc_sets = default_calc_sets; - - /* Recalculate the sets */ - affd->calc_sets(affd, affvecs); - - if (WARN_ON_ONCE(affd->nr_sets > IRQ_AFFINITY_MAX_SETS)) + irq_affinity_calc_sets(affvecs, affd); + if (affd->nr_sets > IRQ_AFFINITY_MAX_SETS) return NULL; /* Nothing to assign? */ Thanks, Ming