From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (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 BDD933370EB; Mon, 12 Jan 2026 15:44:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768232658; cv=none; b=A5NWv5/sO4pxwI6DX0kn1XrZRF2rv9tXgSekQgo0zBW6+AgWT5C3l6bs0Y+GR4DcMwUc+qbQisDX8sueD/K57/ILFoj4jT1MaIrXuSY/7h7wV+k5ReTfW0RAGTt7vL1uwQr/cE8BcTtNP6GEYl39cn2DCswqu0gWv0ktvWM38Mo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768232658; c=relaxed/simple; bh=F+dD0O5rdLlpkSFu3XJPiUpuzGcIGKqS1IYu4fWWxf4=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Pg6f6lRVQBGaEWnaFAJXBlOrEy9cSIVg/jYh2l4Fe7AzMsvwxqDo9AS8BNqrJDjSAKXL7g1+aP2wLvW5cLj99vWjjHNykeoS1C+bBOoCN+KFX3v+vGrdehx01MYKoO4TaNie7LToGd5q1wGmmOKnNIWmFjthNi+gK/4JgT+kNJM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=omZjSHsE; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="omZjSHsE" 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=GHlgTWqk7Lzv2HzCIc5hb0RdKxS5l4uVv2fCHeXt8IA=; b=omZjSHsE59RIJ9X/oCtNVQogsk /zXhvFRscrDOejzz00XtcugWOPBxkTRtZs+reSIvVCvVnJPTaa/Q0GeoQz4XCf2/DyU+xPMf5Dmmw VKtzVKkl9U3BoL7E5lKjpUR0sECg5wZ2FFgqI/NMSdklpxZEnh48icd71Z53h9vwFVX9mSbcTLQQh YwWZSXh1zpooKvZK8fSBbAw6FvG8hAytclWumF5VV+M3h+Vv4MD2TVpgl7WSlz95wIGvN+H7XpPoX nAcAJ+Ncuu7aIUOdFYKaeAuCCPsL9fqXBpIwVRAB/qnm5m78joVWIWDugLPmjTOc3WS6eRBWqVkIo 6qDhhkIQ==; Received: from 2001-1c00-8d85-5700-266e-96ff-fe07-7dcc.cable.dynamic.v6.ziggo.nl ([2001:1c00:8d85:5700:266e:96ff:fe07:7dcc] helo=noisy.programming.kicks-ass.net) by desiato.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1vfK5U-000000015Sc-0C5h; Mon, 12 Jan 2026 15:44:12 +0000 Received: by noisy.programming.kicks-ass.net (Postfix, from userid 1000) id 060AF3030B0; Mon, 12 Jan 2026 16:44:11 +0100 (CET) Date: Mon, 12 Jan 2026 16:44:10 +0100 From: Peter Zijlstra To: Steven Rostedt Cc: Mathieu Desnoyers , Alexei Starovoitov , LKML , Linux trace kernel , bpf , Masami Hiramatsu , "Paul E. McKenney" , Sebastian Andrzej Siewior , Thomas Gleixner , Linus Torvalds Subject: Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast Message-ID: <20260112154410.GA830229@noisy.programming.kicks-ass.net> References: <20260108220550.2f6638f3@fedora> <20260109141930.6deb2a0a@gandalf.local.home> <3c0df437-f6e5-47c6-aed5-f4cc26fe627a@efficios.com> <20260109160202.22975aa4@gandalf.local.home> <20260112153128.GO830755@noisy.programming.kicks-ass.net> <20260112103612.41dd4f03@gandalf.local.home> 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-Disposition: inline In-Reply-To: <20260112103612.41dd4f03@gandalf.local.home> On Mon, Jan 12, 2026 at 10:36:12AM -0500, Steven Rostedt wrote: > On Mon, 12 Jan 2026 16:31:28 +0100 > Peter Zijlstra wrote: > > > > OUCH! So migrate disable/enable has a much larger overhead when executed in > > > a module than in the kernel? This means all spin_locks() in modules > > > converted to mutexes in PREEMPT_RT are taking this hit! > > > > Not so, the migrate_disable() for PREEMPT_RT is still in core code -- > > kernel/locking/spinlock_rt.c is very much not build as a module. > > True. But still, wouldn't it be cleaner to have that variable separate from > the run queue and make the code a bit simpler? I still don't like exporting variables either way around. Exporting functions is much saner.