From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0011.hostedemail.com [216.40.44.11]) (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 5CE991D6187; Fri, 30 Jan 2026 03:31:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769743883; cv=none; b=nvBrWgkv58CD7za2ic8YdWXS18FMItL4amvPdYA3ToCEfkXD+2iLWiCRJZwu/AzNYN3rgchOM4BkdExCF2YnJaA5GVh2SD2ahQvEH6HuQsFK2FUCgIi71C14amNmTPqUpqROf9EI/tgCpzeR3c/JYmWKrOWxoOMJu+irFVME/HY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769743883; c=relaxed/simple; bh=tWZoobf4aGQGPM/wHtCPm5infVuZxqtXkmb9Uav5DsU=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=M6vDwmbHTXbUkDeHQzT/mO3DCrg7e+9SKL+xoXxtK3V7Dqm6HmgvnTuaB+EPdFJ7zEmTXKPYCMzT92EQn2RJVaEmWLpFuzTvhuPbngwmCmdxQcq5/oE+vvmKZ6RKE2MJnbRAfGUgTGWOxRkU54kBRXMa58akakBpUbksHv2fgak= 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=216.40.44.11 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 omf13.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 7C794C181D; Fri, 30 Jan 2026 03:31:19 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf13.hostedemail.com (Postfix) with ESMTPA id 45E3A2000D; Fri, 30 Jan 2026 03:31:17 +0000 (UTC) Date: Thu, 29 Jan 2026 22:31:16 -0500 From: Steven Rostedt To: Yaxiong Tian Cc: Jens Axboe , mhiramat@kernel.org, mathieu.desnoyers@efficios.com, corbet@lwn.net, skhan@linuxfoundation.org, linux-trace-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org Subject: Re: [PATCH v4 5/5] blktrace: Make init_blk_tracer() asynchronous when trace_async_init set Message-ID: <20260129223116.489a01fd@robin> In-Reply-To: <20260129222608.7000bffd@robin> References: <20260128194104.30051be1@gandalf.local.home> <56C8934E-3D17-4467-93E6-D813770BF577@kernel.dk> <20260129152958.05c1ca46@gandalf.local.home> <20260129222608.7000bffd@robin> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-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: rspamout07 X-Rspamd-Queue-Id: 45E3A2000D X-Stat-Signature: if3rqawatujz5jdqhgwskg5u97k9uheo X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1+k5kEN8feabnPqX/jEMae0eAenN2p59D4= X-HE-Tag: 1769743877-885195 X-HE-Meta: U2FsdGVkX1/waOAsEFuCpmccDtR6mGH3uBS3t8ueqKCEeNudKQ7NmVF5Mm3r+p9krEy+K7TnqMG65znftk7tjT05QAjdRiVg4iJNv+uszBEFaV+IT7MMxnnsTKIsH7pKTKizrr57UKZgecc2pAXjD3CF/Oo+CREx0Ge0HHvnXnGS0QYJ62UCf8HU6KCU5Znu2/Gmg1Ws59Ceb/IUvUUK1jyEmxiuWmMVfx5jJ1qkJ9KGBSAFmVhWLl02dEZEbjVoF56N3nnWRRnxuDo9u4yTuEE4ZVMJKKFZgbc+LuU5bqp8/y40o3L706jd7LEIsTnh0PT9gbJpdOOngiKMvuLraWmhyxXkyOe64RiKn/e91PO9DGhR8cpwHJ/XRE8/9zbL On Thu, 29 Jan 2026 22:26:08 -0500 Steven Rostedt wrote: > Use trace_printk() instead. printk now has a "deferred" output. I'm not > sure if the timestamps of when it prints is when the print took place > or when it got to the console :-/ I added the below patch and have this result: kworker/u33:1-79 [002] ..... 1.840855: trace_event_update_all: Start syncing swapper/0-1 [005] ..... 6.045742: trace_eval_sync: sync maps kworker/u33:1-79 [002] ..... 12.289296: trace_event_update_all: Finish syncing swapper/0-1 [005] ..... 12.289387: trace_eval_sync: sync maps complete Which shows that the final initcall waited for the work queue to complete: -- Steve diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 396d59202438..33180d5622a8 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -10817,9 +10817,11 @@ subsys_initcall(trace_eval_init); static int __init trace_eval_sync(void) { + trace_printk("sync maps\n"); /* Make sure the eval map updates are finished */ if (eval_map_wq) destroy_workqueue(eval_map_wq); + trace_printk("sync maps complete\n"); return 0; } diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index af6d1fe5cab7..194b344400e9 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -3555,6 +3555,7 @@ void trace_event_update_all(struct trace_eval_map **map, int len) int last_i; int i; + trace_printk("Start syncing\n"); down_write(&trace_event_sem); list_for_each_entry_safe(call, p, &ftrace_events, list) { /* events are usually grouped together with systems */ @@ -3593,6 +3594,8 @@ void trace_event_update_all(struct trace_eval_map **map, int len) cond_resched(); } up_write(&trace_event_sem); + msleep(10000); + trace_printk("Finish syncing\n"); } static bool event_in_systems(struct trace_event_call *call,