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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8556FC433F5 for ; Tue, 26 Oct 2021 21:23:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5F6E260F6F for ; Tue, 26 Oct 2021 21:23:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239574AbhJZV0Q (ORCPT ); Tue, 26 Oct 2021 17:26:16 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38512 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232059AbhJZV0O (ORCPT ); Tue, 26 Oct 2021 17:26:14 -0400 Received: from desiato.infradead.org (desiato.infradead.org [IPv6:2001:8b0:10b:1:d65d:64ff:fe57:4e05]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 56D6AC061570 for ; Tue, 26 Oct 2021 14:23:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; 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; bh=pUBzPUdB110mn7Gg7YEa/AEceHnmilwE6ZqD1nGsNeE=; b=pCLU+GwD18uZSwjeK6yLP2cDkq t/ZtBh4A0YFbwWF7EBY43+IYRtV1/zOvxH9pOlmDttZjN7BH3f6oZusgjoksYWzx3IGb5nVFqHrlL U3IhUBYiFEbS84zxuBBzJa4F01V8E/aO/yAEfqmm9YnixEFO3zRAi48Y7QqXU+7LoMZ1vMvEq5a6B 9W/jxSFjDA1yEeYrehlhc/nhZoSNAYMJv3NnnkhWu0WbbRgRlufV2RWS5YXKPhggsR3tBygsfHa23 FqliHuM2NSzvk4oGOYwo97fnJF56ncaivWHHmPuRgs1E3lN5nvlzmiY2E0hM4Jfhn2ISau4XbYTlC EEac3GRQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.94.2 #2 (Red Hat Linux)) id 1mfTuw-00CQjf-7x; Tue, 26 Oct 2021 21:23:34 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 0175B3002AE; Tue, 26 Oct 2021 23:23:32 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id DF49F2C1D557D; Tue, 26 Oct 2021 23:23:32 +0200 (CEST) Date: Tue, 26 Oct 2021 23:23:32 +0200 From: Peter Zijlstra To: Steven Rostedt Cc: "Robin H. Johnson" , linux-kernel@vger.kernel.org, mingo@redhat.com, rjohnson@digitalocean.com, Arnaldo Carvalho de Melo Subject: Re: [PATCH 1/2] tracing: show size of requested buffer Message-ID: References: <20210831043723.13481-1-robbat2@gentoo.org> <20210907212426.73ed81d1@rorschach.local.home> <20211007071151.GL174703@worktop.programming.kicks-ass.net> <20211007092358.65152792@gandalf.local.home> <20211026164343.2e1754bd@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211026164343.2e1754bd@gandalf.local.home> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Oct 26, 2021 at 04:43:43PM -0400, Steven Rostedt wrote: > On Thu, 7 Oct 2021 09:23:58 -0400 > Steven Rostedt wrote: > > > On Thu, 7 Oct 2021 09:11:51 +0200 > > Peter Zijlstra wrote: > > > > > > > +++ b/kernel/trace/trace_event_perf.c > > > > > @@ -400,7 +400,8 @@ void *perf_trace_buf_alloc(int size, struct pt_regs **regs, int *rctxp) > > > > > BUILD_BUG_ON(PERF_MAX_TRACE_SIZE % sizeof(unsigned long)); > > > > > > > > > > if (WARN_ONCE(size > PERF_MAX_TRACE_SIZE, > > > > > - "perf buffer not large enough")) > > > > > + "perf buffer not large enough, wanted %d, have %d", > > > > > + size, PERF_MAX_TRACE_SIZE)) > > > > > > Priting a constant seems daft.. why is any of this important in any way? > > > > I see your point, but it can be useful if you changed it, and want to know > > if you are running the kernel with the change or not. > > > > I've done daft things were I changed a const and was running a kernel > > without the change and couldn't understand why it wasn't working ;-) > > Peter, > > Do you have any real issue if I just take this patch set through my tree? No real objections; just weary, huge events like that are fairly sucky for performance.