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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,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 BEDFCC43142 for ; Fri, 22 Jun 2018 12:30:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 835BD241DB for ; Fri, 22 Jun 2018 12:30:58 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 835BD241DB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=zytor.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752416AbeFVMa4 (ORCPT ); Fri, 22 Jun 2018 08:30:56 -0400 Received: from terminus.zytor.com ([198.137.202.136]:51971 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751209AbeFVMay (ORCPT ); Fri, 22 Jun 2018 08:30:54 -0400 Received: from terminus.zytor.com (localhost [127.0.0.1]) by terminus.zytor.com (8.15.2/8.15.2) with ESMTPS id w5MCUldJ067521 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO); Fri, 22 Jun 2018 05:30:47 -0700 Received: (from tipbot@localhost) by terminus.zytor.com (8.15.2/8.15.2/Submit) id w5MCUlEA067518; Fri, 22 Jun 2018 05:30:47 -0700 Date: Fri, 22 Jun 2018 05:30:47 -0700 X-Authentication-Warning: terminus.zytor.com: tipbot set sender to tipbot@zytor.com using -f From: tip-bot for Eric Dumazet Message-ID: Cc: mingo@kernel.org, edumazet@google.com, tglx@linutronix.de, linux-kernel@vger.kernel.org, eric.dumazet@gmail.com, hpa@zytor.com Reply-To: edumazet@google.com, tglx@linutronix.de, mingo@kernel.org, linux-kernel@vger.kernel.org, hpa@zytor.com, eric.dumazet@gmail.com In-Reply-To: <20180620150332.163320-1-edumazet@google.com> References: <20180620150332.163320-1-edumazet@google.com> To: linux-tip-commits@vger.kernel.org Subject: [tip:irq/core] genirq: Speedup show_interrupts() Git-Commit-ID: 74bdf7815dfb3805a37b0bba615814063a227bf5 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: 74bdf7815dfb3805a37b0bba615814063a227bf5 Gitweb: https://git.kernel.org/tip/74bdf7815dfb3805a37b0bba615814063a227bf5 Author: Eric Dumazet AuthorDate: Wed, 20 Jun 2018 08:03:32 -0700 Committer: Thomas Gleixner CommitDate: Fri, 22 Jun 2018 14:22:58 +0200 genirq: Speedup show_interrupts() Since commit 425a5072dcd1 ("genirq: Free irq_desc with rcu"), show_interrupts() can be switched to rcu locking, which removes possible contention on sparse_irq_lock. The per_cpu count scan and print can be done without holding desc spinlock. And there is no need to call kstat_irqs_cpu() and abuse irq_to_desc() while holding rcu read lock, since desc and desc->kstat_irqs wont disappear or change. Signed-off-by: Eric Dumazet Signed-off-by: Thomas Gleixner Cc: Eric Dumazet Link: https://lkml.kernel.org/r/20180620150332.163320-1-edumazet@google.com --- kernel/irq/proc.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-) diff --git a/kernel/irq/proc.c b/kernel/irq/proc.c index 37eda10f5c36..da9addb8d655 100644 --- a/kernel/irq/proc.c +++ b/kernel/irq/proc.c @@ -475,22 +475,24 @@ int show_interrupts(struct seq_file *p, void *v) seq_putc(p, '\n'); } - irq_lock_sparse(); + rcu_read_lock(); desc = irq_to_desc(i); if (!desc) goto outsparse; - raw_spin_lock_irqsave(&desc->lock, flags); - for_each_online_cpu(j) - any_count |= kstat_irqs_cpu(i, j); - action = desc->action; - if ((!action || irq_desc_is_chained(desc)) && !any_count) - goto out; + if (desc->kstat_irqs) + for_each_online_cpu(j) + any_count |= *per_cpu_ptr(desc->kstat_irqs, j); + + if ((!desc->action || irq_desc_is_chained(desc)) && !any_count) + goto outsparse; seq_printf(p, "%*d: ", prec, i); for_each_online_cpu(j) - seq_printf(p, "%10u ", kstat_irqs_cpu(i, j)); + seq_printf(p, "%10u ", desc->kstat_irqs ? + *per_cpu_ptr(desc->kstat_irqs, j) : 0); + raw_spin_lock_irqsave(&desc->lock, flags); if (desc->irq_data.chip) { if (desc->irq_data.chip->irq_print_chip) desc->irq_data.chip->irq_print_chip(&desc->irq_data, p); @@ -511,6 +513,7 @@ int show_interrupts(struct seq_file *p, void *v) if (desc->name) seq_printf(p, "-%-8s", desc->name); + action = desc->action; if (action) { seq_printf(p, " %s", action->name); while ((action = action->next) != NULL) @@ -518,10 +521,9 @@ int show_interrupts(struct seq_file *p, void *v) } seq_putc(p, '\n'); -out: raw_spin_unlock_irqrestore(&desc->lock, flags); outsparse: - irq_unlock_sparse(); + rcu_read_unlock(); return 0; } #endif