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=-12.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 A6ECBC282C2 for ; Sun, 10 Feb 2019 20:55:49 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6E9CB2146F for ; Sun, 10 Feb 2019 20:55:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726796AbfBJUzr (ORCPT ); Sun, 10 Feb 2019 15:55:47 -0500 Received: from terminus.zytor.com ([198.137.202.136]:53079 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726096AbfBJUzr (ORCPT ); Sun, 10 Feb 2019 15:55:47 -0500 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id x1AKt4SA3235652 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Sun, 10 Feb 2019 12:55:04 -0800 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id x1AKt1MU3235592; Sun, 10 Feb 2019 12:55:01 -0800 Date: Sun, 10 Feb 2019 12:55:01 -0800 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Thomas Gleixner Message-ID: Cc: marc.zyngier@arm.com, akpm@linux-foundation.org, mingo@kernel.org, dbueso@suse.de, david@fromorbit.com, willy@infradead.org, miklos@szeredi.hu, rdunlap@infradead.org, tglx@linutronix.de, dave@stgolabs.net, adobriyan@gmail.com, dancol@google.com, keescook@chromium.org, longman@redhat.com, linux-kernel@vger.kernel.org, hpa@zytor.com Reply-To: mingo@kernel.org, akpm@linux-foundation.org, marc.zyngier@arm.com, dbueso@suse.de, david@fromorbit.com, willy@infradead.org, miklos@szeredi.hu, rdunlap@infradead.org, tglx@linutronix.de, adobriyan@gmail.com, dave@stgolabs.net, linux-kernel@vger.kernel.org, dancol@google.com, keescook@chromium.org, longman@redhat.com, hpa@zytor.com In-Reply-To: <20190208135020.925487496@linutronix.de> References: <20190208135020.925487496@linutronix.de> To: linux-tip-commits@vger.kernel.org Subject: [tip:irq/core] genirq: Avoid summation loops for /proc/stat Git-Commit-ID: 1136b0728969901a091f0471968b2b76ed14d9ad X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 1136b0728969901a091f0471968b2b76ed14d9ad Gitweb: https://git.kernel.org/tip/1136b0728969901a091f0471968b2b76ed14d9ad Author: Thomas Gleixner AuthorDate: Fri, 8 Feb 2019 14:48:03 +0100 Committer: Thomas Gleixner CommitDate: Sun, 10 Feb 2019 21:34:45 +0100 genirq: Avoid summation loops for /proc/stat Waiman reported that on large systems with a large amount of interrupts the readout of /proc/stat takes a long time to sum up the interrupt statistics. In principle this is not a problem. but for unknown reasons some enterprise quality software reads /proc/stat with a high frequency. The reason for this is that interrupt statistics are accounted per cpu. So the /proc/stat logic has to sum up the interrupt stats for each interrupt. This can be largely avoided for interrupts which are not marked as 'PER_CPU' interrupts by simply adding a per interrupt summation counter which is incremented along with the per interrupt per cpu counter. The PER_CPU interrupts need to avoid that and use only per cpu accounting because they share the interrupt number and the interrupt descriptor and concurrent updates would conflict or require unwanted synchronization. Reported-by: Waiman Long Signed-off-by: Thomas Gleixner Reviewed-by: Waiman Long Reviewed-by: Marc Zyngier Reviewed-by: Davidlohr Bueso Cc: Matthew Wilcox Cc: Andrew Morton Cc: Alexey Dobriyan Cc: Kees Cook Cc: linux-fsdevel@vger.kernel.org Cc: Davidlohr Bueso Cc: Miklos Szeredi Cc: Daniel Colascione Cc: Dave Chinner Cc: Randy Dunlap Link: https://lkml.kernel.org/r/20190208135020.925487496@linutronix.de 8<------------- v2: Undo the unintentional layout change of struct irq_desc. include/linux/irqdesc.h | 1 + kernel/irq/chip.c | 12 ++++++++++-- kernel/irq/internals.h | 8 +++++++- kernel/irq/irqdesc.c | 7 ++++++- 4 files changed, 24 insertions(+), 4 deletions(-) --- include/linux/irqdesc.h | 1 + kernel/irq/chip.c | 12 ++++++++++-- kernel/irq/internals.h | 8 +++++++- kernel/irq/irqdesc.c | 7 ++++++- 4 files changed, 24 insertions(+), 4 deletions(-) diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h index dd1e40ddac7d..875c41b23f20 100644 --- a/include/linux/irqdesc.h +++ b/include/linux/irqdesc.h @@ -65,6 +65,7 @@ struct irq_desc { unsigned int core_internal_state__do_not_mess_with_it; unsigned int depth; /* nested irq disables */ unsigned int wake_depth; /* nested wake enables */ + unsigned int tot_count; unsigned int irq_count; /* For detecting broken IRQs */ unsigned long last_unhandled; /* Aging timer for unhandled count */ unsigned int irqs_unhandled; diff --git a/kernel/irq/chip.c b/kernel/irq/chip.c index 34e969069488..e960c4f46ee0 100644 --- a/kernel/irq/chip.c +++ b/kernel/irq/chip.c @@ -855,7 +855,11 @@ void handle_percpu_irq(struct irq_desc *desc) { struct irq_chip *chip = irq_desc_get_chip(desc); - kstat_incr_irqs_this_cpu(desc); + /* + * PER CPU interrupts are not serialized. Do not touch + * desc->tot_count. + */ + __kstat_incr_irqs_this_cpu(desc); if (chip->irq_ack) chip->irq_ack(&desc->irq_data); @@ -884,7 +888,11 @@ void handle_percpu_devid_irq(struct irq_desc *desc) unsigned int irq = irq_desc_get_irq(desc); irqreturn_t res; - kstat_incr_irqs_this_cpu(desc); + /* + * PER CPU interrupts are not serialized. Do not touch + * desc->tot_count. + */ + __kstat_incr_irqs_this_cpu(desc); if (chip->irq_ack) chip->irq_ack(&desc->irq_data); diff --git a/kernel/irq/internals.h b/kernel/irq/internals.h index ca6afa267070..e74e7eea76cf 100644 --- a/kernel/irq/internals.h +++ b/kernel/irq/internals.h @@ -242,12 +242,18 @@ static inline void irq_state_set_masked(struct irq_desc *desc) #undef __irqd_to_state -static inline void kstat_incr_irqs_this_cpu(struct irq_desc *desc) +static inline void __kstat_incr_irqs_this_cpu(struct irq_desc *desc) { __this_cpu_inc(*desc->kstat_irqs); __this_cpu_inc(kstat.irqs_sum); } +static inline void kstat_incr_irqs_this_cpu(struct irq_desc *desc) +{ + __kstat_incr_irqs_this_cpu(desc); + desc->tot_count++; +} + static inline int irq_desc_get_node(struct irq_desc *desc) { return irq_common_data_get_node(&desc->irq_common_data); diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c index ee062b7939d3..f98293d0e173 100644 --- a/kernel/irq/irqdesc.c +++ b/kernel/irq/irqdesc.c @@ -119,6 +119,7 @@ static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node, desc->depth = 1; desc->irq_count = 0; desc->irqs_unhandled = 0; + desc->tot_count = 0; desc->name = NULL; desc->owner = owner; for_each_possible_cpu(cpu) @@ -919,11 +920,15 @@ unsigned int kstat_irqs_cpu(unsigned int irq, int cpu) unsigned int kstat_irqs(unsigned int irq) { struct irq_desc *desc = irq_to_desc(irq); - int cpu; unsigned int sum = 0; + int cpu; if (!desc || !desc->kstat_irqs) return 0; + if (!irq_settings_is_per_cpu_devid(desc) && + !irq_settings_is_per_cpu(desc)) + return desc->tot_count; + for_each_possible_cpu(cpu) sum += *per_cpu_ptr(desc->kstat_irqs, cpu); return sum;