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=-1.0 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 0742BC04EBF for ; Tue, 4 Dec 2018 22:33:04 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AC7FF20851 for ; Tue, 4 Dec 2018 22:33:03 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AC7FF20851 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=goodmis.org 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 S1726305AbeLDWdC (ORCPT ); Tue, 4 Dec 2018 17:33:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:57650 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725899AbeLDWdC (ORCPT ); Tue, 4 Dec 2018 17:33:02 -0500 Received: from vmware.local.home (unknown [208.91.3.26]) (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 8CA1820850; Tue, 4 Dec 2018 22:33:01 +0000 (UTC) Date: Tue, 4 Dec 2018 17:32:58 -0500 From: Steven Rostedt To: Anders Roxell Cc: mingo@redhat.com, catalin.marinas@arm.com, will.deacon@arm.com, keescook@chromium.org, arnd@arndb.de, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org Subject: Re: [PATCH v3] tracing: add cond_resched to ftrace_replace_code() Message-ID: <20181204173258.6de70c66@vmware.local.home> In-Reply-To: <20181204194044.9506-1-anders.roxell@linaro.org> References: <20181204194044.9506-1-anders.roxell@linaro.org> X-Mailer: Claws Mail 3.15.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 4 Dec 2018 20:40:44 +0100 Anders Roxell wrote: > When running in qemu on an kernel built with allmodconfig and debug > options (in particular kcov and ubsan) enabled, ftrace_replace_code > function call take minutes. The ftrace selftest calls > ftrace_replace_code to look >40000 through > ftrace_make_call/ftrace_make_nop, and these end up calling > __aarch64_insn_write/aarch64_insn_patch_text_nosync. > > Microseconds add up because this is called in a loop for each dyn_ftrace > record, and this triggers the softlockup watchdog unless we let it sleep > occasionally. > > Rework so that we call cond_resched() if !irqs_disabled() && !preempt_count(). This isn't urgent is it? That is, it doesn't need a stable tag? -- Steve