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=-2.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT 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 929A1C43441 for ; Thu, 22 Nov 2018 10:08:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 50D7920866 for ; Thu, 22 Nov 2018 10:08:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="ggfGQ+b1" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 50D7920866 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.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 S2393846AbeKVUrR (ORCPT ); Thu, 22 Nov 2018 15:47:17 -0500 Received: from merlin.infradead.org ([205.233.59.134]:37294 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731910AbeKVUrR (ORCPT ); Thu, 22 Nov 2018 15:47:17 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=9dCNxHqs5TlkEwajsCnPG0CfSw08S5QtKEYhjimDs00=; b=ggfGQ+b1Mq/5L2PmH/+4Ws9Pg mZOCUerw3fa9nnmnEo8NDMNKpu96yFssgjuM4s4sUvJqkgIUiETPzP4Aai82JdQdqLvUOLrnx+cuj uhuBixZ/XSYaZkPJ1Hrz/nklIsLYROKy1W76YlyOpWEcO6AU+bTiW/kELpXvXAQcA5Xmc068GsbUx 11XqlZWi/BhNLKKe+cFaFtskTKjktYw03PiQXI2BXFQzFEUj4qy/Z7RMYvGSqAd14rrDDgiBtrEPu 1/wRkiz/RzCEJwe28xN2x6w9hny4rsF9MYqWWI8BQYjvxp1cSTsjl4qtg0QZ/6WOrKfECav6msU8n BFSJjK9zw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gPluH-0000Iz-Ig; Thu, 22 Nov 2018 10:08:22 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2B4A42029FD58; Thu, 22 Nov 2018 11:08:12 +0100 (CET) Date: Thu, 22 Nov 2018 11:08:12 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Thomas Gleixner , Masami Hiramatsu , Josh Poimboeuf , Frederic Weisbecker , Joel Fernandes , Andy Lutomirski , Mark Rutland Subject: Re: [RFC][PATCH 00/14] function_graph: Rewrite to allow multiple users Message-ID: <20181122100812.GO2131@hirez.programming.kicks-ass.net> References: <20181122012708.491151844@goodmis.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181122012708.491151844@goodmis.org> 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 On Wed, Nov 21, 2018 at 08:27:08PM -0500, Steven Rostedt wrote: > Well the fuction graph tracer is arguably the strongest of the tracers. > It shows both the entrance and exit of a function, can give the timings > of a function, and shows the execution of the code quite nicely. > > But it has one major flaw. > > It can't let more than one user access it at a time. The reason I 'never' use it is performance, it _sucks_.. I've never ran into the multi-user issue. So while I don't think the rewrite is bad, this argument here is.