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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_2 autolearn=no 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 BBD2CC433DF for ; Sun, 28 Jun 2020 19:00:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9F233206D7 for ; Sun, 28 Jun 2020 19:00:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726668AbgF1TAT (ORCPT ); Sun, 28 Jun 2020 15:00:19 -0400 Received: from mail.kernel.org ([198.145.29.99]:36988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726585AbgF1TAS (ORCPT ); Sun, 28 Jun 2020 15:00:18 -0400 Received: from oasis.local.home (cpe-66-24-58-225.stny.res.rr.com [66.24.58.225]) (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 94A6E206C0; Sun, 28 Jun 2020 19:00:16 +0000 (UTC) Date: Sun, 28 Jun 2020 15:00:15 -0400 From: Steven Rostedt To: Alexei Starovoitov Cc: Nicolas Boichat , LKML , Ingo Molnar , Andrew Morton , Kees Cook , Jason Gunthorpe , Daniel Vetter , Peter Zijlstra , Vinod Koul , Andy Shevchenko , Alexey Dobriyan , Tiezhu Yang , Thomas Gleixner , "Guilherme G . Piccoli" , Will Deacon , Douglas Anderson , Guenter Roeck , bpf@vger.kernel.org Subject: Re: [PATCH] kernel/trace: Add TRACING_ALLOW_PRINTK config option Message-ID: <20200628150015.363009dd@oasis.local.home> In-Reply-To: <20200628144616.52f09152@oasis.local.home> References: <20200624084524.259560-1-drinkcat@chromium.org> <20200624120408.12c8fa0d@oasis.local.home> <20200625035913.z4setdowrgt4sqpd@ast-mbp.dhcp.thefacebook.com> <20200626181455.155912d9@oasis.local.home> <20200628172700.5ea422tmw77otadn@ast-mbp.dhcp.thefacebook.com> <20200628144616.52f09152@oasis.local.home> X-Mailer: Claws Mail 3.17.3 (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: bpf-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org On Sun, 28 Jun 2020 14:46:16 -0400 Steven Rostedt wrote: > > We added a bunch of code to libbcc in the past to support instances, > > but eventually removed it all due to memory overhead per instance. > > If I recall it was ~8Mbyte per instance. That was couple years ago. > > I'd like to see where that 8 MB per instance came from. You can control > the size of the instance buffers. If size is still an issue, I'll be > happy to work with you to fix it. Looks to be the duplication of the event directory tree. There's a lot of duplicate data there. Instead of just punting and saying "instances are too large" perhaps you could get someone to look at a way to consolidate that data? I'm sure there's a lot of ways to help here. Or you can just create a new event called bpf_printk() that passes in and records a string and enable that automatically when a bpf module has it. That could work as well. In either case, your use of trace_printk() is an abuse of its purpose. -- Steve