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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 90275C2BA2B for ; Thu, 9 Apr 2020 10:40:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6F50820757 for ; Thu, 9 Apr 2020 10:40:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726684AbgDIKkh (ORCPT ); Thu, 9 Apr 2020 06:40:37 -0400 Received: from outbound-smtp46.blacknight.com ([46.22.136.58]:46387 "EHLO outbound-smtp46.blacknight.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725828AbgDIKkh (ORCPT ); Thu, 9 Apr 2020 06:40:37 -0400 Received: from mail.blacknight.com (pemlinmail05.blacknight.ie [81.17.254.26]) by outbound-smtp46.blacknight.com (Postfix) with ESMTPS id 5E507FACA9 for ; Thu, 9 Apr 2020 11:40:36 +0100 (IST) Received: (qmail 26492 invoked from network); 9 Apr 2020 10:40:36 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.18.57]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 9 Apr 2020 10:40:36 -0000 Date: Thu, 9 Apr 2020 11:40:34 +0100 From: Mel Gorman To: Joel Fernandes Cc: Peter Zijlstra , Namhyung Kim , Steven Rostedt , Linux Kernel Mailing List Subject: [PATCH] tracing: Remove obsolete PREEMPTIRQ_EVENTS kconfig option Message-ID: <20200409104034.GJ3818@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The PREEMPTIRQ_EVENTS option is unused after commit c3bc8fd637a9 ("tracing: Centralize preemptirq tracepoints and unify their usage"). Remove it. Note that this option is hazardous as it stands. It enables TRACE_IRQFLAGS event on non-preempt configurations without the irqsoff tracer enabled. TRACE_IRQFLAGS as it stands incurs significant overhead on each IRQ entry/exit. This is because trace_hardirqs_[on|off] does all the per-cpu manipulations and NMI checks even if tracing is completely disabled for some insane reason. For example, netperf running UDP_STREAM on localhost incurs a 4-6% performance penalty without any tracing if IRQFLAGS is set. It can be put behind a static brach but even the function entry/exit costs a little bit. Signed-off-by: Mel Gorman --- kernel/trace/Kconfig | 9 --------- 1 file changed, 9 deletions(-) diff --git a/kernel/trace/Kconfig b/kernel/trace/Kconfig index 402eef84c859..568ad371e19c 100644 --- a/kernel/trace/Kconfig +++ b/kernel/trace/Kconfig @@ -258,15 +258,6 @@ config TRACE_PREEMPT_TOGGLE Enables hooks which will be called when preemption is first disabled, and last enabled. -config PREEMPTIRQ_EVENTS - bool "Enable trace events for preempt and irq disable/enable" - select TRACE_IRQFLAGS - select TRACE_PREEMPT_TOGGLE if PREEMPTION - select GENERIC_TRACER - default n - help - Enable tracing of disable and enable events for preemption and irqs. - config IRQSOFF_TRACER bool "Interrupts-off Latency Tracer" default n