From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 719712D46BD; Fri, 30 Jan 2026 09:30:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769765427; cv=none; b=CcNbrvFYkQu/ClHz5d7wruqzgKwIzyPcnBXtgkYYkrnN/xFvb+72USTkFQRwWs+BBvvnmdbDsUEsNz4q2YhqfF7jIWKPUp6bqYVML9LumrNcscvTWULJDPFQyUB0bjQuBGg7aUafU/2ajniAXeqACtIGVJDgusNk+qNGicT20Xs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1769765427; c=relaxed/simple; bh=A/e93zSeuScuKLLv1EFCsZiYkVthcJkWuJEGlAY6QNA=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=m0v5sH2YubUZNNK8NGFIuA0/tWLTns4HE9rj04aK4gPb8+/88ueTBJ0QEc9b7kosWiLioe+gYcGCPhk4ILSKFdc5iao7F7BX/z1BbFJ+D6dq+AyhnjoSlfSLHDg0GLsExPn8EEn52BBb5Xo+uIysMaL7CvHORhgPO4CppLX1LQc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=HlD0gqm0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="HlD0gqm0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6CE07C4CEF7; Fri, 30 Jan 2026 09:30:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1769765427; bh=A/e93zSeuScuKLLv1EFCsZiYkVthcJkWuJEGlAY6QNA=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=HlD0gqm0fh9rqu+5ydFFnqQtErkuE9CoVB+/MavUxoVktSjloZfIrJSoAi5hg0nzb XCAE5/NqZy5qB2LXxPTe5hkAjEiuA4FwnhS703qLkWjEucPKAoEzGiPsz8JP/3oeQR uKNsQ+vEd8FsqBdQ/Zx6lLV3HlEn+ZiRtsFUHrfT2T4DgVXdihki7fuiCrkMHyZbAh +ecbxd5fVgcfF3AuhGg49xGfR23mhawtxUKLe741QureYgx9rZqPnj31n9kgLJleiZ /SIxaVLkVHwcquEJ/WRFc7zaihxSOGxwVaQutjXE2v0eYDNZFg+I3pmsTMwaWq1TPc na8vW5szw2nTw== Date: Fri, 30 Jan 2026 18:30:22 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: Jens Axboe , Yaxiong Tian , 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: <20260130183022.add316050dd9638e6d71a469@kernel.org> In-Reply-To: <20260129152958.05c1ca46@gandalf.local.home> References: <20260128194104.30051be1@gandalf.local.home> <56C8934E-3D17-4467-93E6-D813770BF577@kernel.dk> <20260129152958.05c1ca46@gandalf.local.home> X-Mailer: Sylpheed 3.8.0beta1 (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=UTF-8 Content-Transfer-Encoding: 8bit On Thu, 29 Jan 2026 15:29:58 -0500 Steven Rostedt wrote: > On Wed, 28 Jan 2026 19:25:46 -0700 > Jens Axboe wrote: > > > On Jan 28, 2026, at 5:40 PM, Steven Rostedt wrote: > > > > > >  > > > Jens, > > > > > > Can you give me an acked-by on this patch and I can take the series through > > > my tree. > > > > On phone, hope this works: > > > > Acked-by: Jens Axboe > > Thanks! > > > > > > Or perhaps this doesn't even need to test the trace_async_init flag and can > > > always do the work queue? Does blk_trace ever do tracing at boot up? That > > > is, before user space starts? > > > > Not via the traditonal way of running blktrace. > > Masami and Yaxiong, > > I've been thinking about this more and I'm not sure we need the > trace_async_init kernel parameter at all. As blktrace should only be > enabled by user space, it can always use the work queue. > > For kprobes, if someone is adding a kprobe on the kernel command line, then > they are already specifying that tracing is more important. > > Patch 3 already keeps kprobes from being an issue with contention of the > tracing locks, so I don't think it ever needs to use the work queue. > > Wouldn't it just be better to remove the trace_async_init and make blktrace > always use the work queue and kprobes never do it (but exit out early if > there were no kprobes registered)? Yeah, for kprobes event case, that sounds good to me. I think [3/5] is enough to speed it up if user does not define kprobe events on cmdline. Thank you, > > That is, remove patch 2 and 4 and make this patch always use the work queue. > > -- Steve -- Masami Hiramatsu (Google)