Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933480AbZINSl2 (ORCPT ); Mon, 14 Sep 2009 14:41:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933133AbZINSl1 (ORCPT ); Mon, 14 Sep 2009 14:41:27 -0400 Received: from ey-out-2122.google.com ([74.125.78.24]:56315 "EHLO ey-out-2122.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933004AbZINSl0 (ORCPT ); Mon, 14 Sep 2009 14:41:26 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:references:mime-version :content-type:content-disposition:in-reply-to:user-agent; b=u81QydKYW79Dqh0Zao4X/0qlfYmBAOwg1+IDDrQ6Xbnoka+Y9RuG8NPYCmEevEmGmR XHSVQLEbmHnNBabDoyC6gqCsYD+yWDfnMSgqqi6n7aToa+JZjAjgACsvMtnT7Nw1JJIi em80epXEtqmWF1y3zSiWVGq4f79gz157c33iw= Date: Mon, 14 Sep 2009 20:41:24 +0200 From: Frederic Weisbecker To: Steven Rostedt , Peter Zijlstra Cc: Christopher Li , Jaswinder Singh Rajput , Ingo Molnar , Stephen Rothwell , Thomas Gleixner , "H. Peter Anvin" , linux-next@vger.kernel.org, linux-kernel@vger.kernel.org, linux-sparse@vger.kernel.org, Josh Triplett Subject: Re: Warning from ring buffer code (Was: Re: linux-next: tip tree build warning) Message-ID: <20090914184123.GC6045@nowhere> References: <20090804161640.70817ee6.sfr@canb.auug.org.au> <1249403089.4634.139.camel@localhost.localdomain> <20090912165300.9d257283.sfr@canb.auug.org.au> <20090912073906.GA3972@elte.hu> <1252753957.12217.10.camel@ht.satnam> <1252941416.2964.143.camel@localhost.localdomain> <70318cbf0909141009v46581785m4c70edf31fcb79fa@mail.gmail.com> <1252952238.2964.154.camel@localhost.localdomain> <1252952621.31964.0.camel@twins> <1252953076.2964.156.camel@localhost.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1252953076.2964.156.camel@localhost.localdomain> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1196 Lines: 30 On Mon, Sep 14, 2009 at 02:31:16PM -0400, Steven Rostedt wrote: > On Mon, 2009-09-14 at 20:23 +0200, Peter Zijlstra wrote: > > On Mon, 2009-09-14 at 14:17 -0400, Steven Rostedt wrote: > > > Frederic, how big can one of those events get. The ring buffer (and > > > TRACE_EVENT) allow up to almost a page size, which is very hefty for the > > > stack. This code needs to either be rewritten or we need to set a limit > > > to the size of a profile entry. > > > > Yeah, that needs to get a re-write.. I've complained about this when it > > went in. > > One answer is to create a per cpu buffer that is big enough to hold the > data needed. Then you can disable interrupts an use it without worry. > > If you need to also handle NMIs, then create a per_cpu NMI buffer too, > and use that if "in_nmi()" is true. > > -- Steve Looks like a nice idea. Peter, does that sound acceptable to you to disable interrupts during a profiled tracepoint event? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/