From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0012.hostedemail.com [216.40.44.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id E79784779A5; Wed, 1 Apr 2026 14:40:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.12 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775054430; cv=none; b=HNuXIc87zyhklYqN4DyXtAssNOrk/zdApr/oPm4xLCrAeBK+tB8655V/s+DRguuYcp3Hf+dNb3kTCKVJL33P8qWEYv0eRh6w+iYSQXKZtSycEe+iWtavQwTRtKZP1KRfpTcfSK597WNcQ3b/d2aGB1kHSOx+1Ecu3sHXB0uBBWs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775054430; c=relaxed/simple; bh=Va7sdOM42iHClAcV5UsPJ/Z7QJQwex4SsOc4e6A691k=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=YM5a9V6M4xP3GRio9R0xM4oR65JTB8LQMUoReTRPXu+b/pRFLgwI2lEpwSYUHYDPwkGmmLq1OJQkELtXen3n/HsMEYueWSKAfOj8SmrY4dGJotFi7TAD0ZfP3AjiMg5dppWYbOlBO2HeC1B7AI5TZVHIyJff+gBqsK+4GWI3Lng= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org; spf=pass smtp.mailfrom=goodmis.org; arc=none smtp.client-ip=216.40.44.12 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=goodmis.org Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=goodmis.org Received: from omf16.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id D205514094A; Wed, 1 Apr 2026 14:40:21 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf16.hostedemail.com (Postfix) with ESMTPA id 01D4720013; Wed, 1 Apr 2026 14:40:19 +0000 (UTC) Date: Wed, 1 Apr 2026 10:41:20 -0400 From: Steven Rostedt To: "Masami Hiramatsu (Google)" Cc: Mathieu Desnoyers , linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: Re: [PATCH v9 3/3] tracing/Documentation: Add a section about backup instance Message-ID: <20260401104120.0e4a364a@gandalf.local.home> In-Reply-To: <20260401121541.e2c8c549ae172ccf2d5e3035@kernel.org> References: <177497473558.569199.6527680985537865638.stgit@mhiramat.tok.corp.google.com> <177497476117.569199.18085846838539980210.stgit@mhiramat.tok.corp.google.com> <20260331172105.609d59aa@gandalf.local.home> <20260401121541.e2c8c549ae172ccf2d5e3035@kernel.org> X-Mailer: Claws Mail 3.20.0git84 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspamout05 X-Rspamd-Queue-Id: 01D4720013 X-Stat-Signature: gh1po3cyb937saonukdxhdzs94fsm5oa X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+ORugR7/XsZXsHFVkD2bE2kkzCXP3+eaw= X-HE-Tag: 1775054419-894820 X-HE-Meta: U2FsdGVkX1+ZvXSFD3OohE0Zm7RJKnbNK5lTmXj2m9geKDELPSNfl5vf6w5BYH19r7z8pPLkDcJPwVtaxMd18L3K0uGOztGpzdB1mkbXGpno44sfcWW0nRxoS45ycWqk9MZljT64XNWdPjOBKO3xpUw52fRe0Eo3dCApq3mSlMf1X+ubSJ0zkV3wBI8ODbYFaz4VyNGHQ7CmaYecGlr05IqgNrDUjbHv2hydpLh1dw/oxUZhJiTBEOYbnNUqsvahMi9nCbgc+QdvuoWJAm7Xw2XSSqQVeK9vPHp+yzJgeaZu87YVJOXYZ1odnf/kWdD+LTs1yLE4YkPaquda+U4YgGofk5LV+b/4 On Wed, 1 Apr 2026 12:15:41 +0900 Masami Hiramatsu (Google) wrote: > > > +It is also possible to record trace data at system boot time by specifying > > > +events with the persistent ring buffer, but in this case the data before the > > > +reboot will be lost before it can be read. This problem can be solved by a > > > +backup instance. From the kernel command line:: > > > + > > > + reserve_mem=12M:4096:trace trace_instance=boot_map@trace,sched,irq trace_instance=backup=boot_map > > > > The above didn't actually work well without my patch to enable events on > > the persistent ring buffer with the backup. But keep it, as it will work > > with my patch ;-) > > Ah, thanks! > Let me rebase on it. Well, my patch hasn't been added yet ;-) But don't change anything. When this goes upstream both patches should have been applied. -- Steve