From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) (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 C409EB640; Fri, 9 Jan 2026 22:00:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=216.40.44.15 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767996041; cv=none; b=U5oeDjeD+7qwnLRyNNwnjw4HDPgIJccuUFigdYxy+SVcNnZikcTNHr41JqzV6rQZRdocxBRGT/vQ/vFVqMY/vs9AIpJuxt552K6CF77soRMl0TePUdQFtRoSjMeSEPAlQYu9cNw4OtVfg8hxcpX5+8X94gKK17ZYQ7yqZHMVDxg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1767996041; c=relaxed/simple; bh=2b//BR2IDYW15K0i4zqJVCCHK8/tQaGKGIDk4oXExNg=; h=Date:From:To:Cc:Subject:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=ev9iVCDDFzvnPlwZ17oMbiEmDKuiMa3ZUIOF+RU4634loUf3i2ZmwzlPOqDl1/5M+LrNKuXuydzhLKiEQRGAB8Z9qwampNtZIRlcUzZfGi5WTs17fs138xWdDsr72kbD9O60nzfqKKm2EPwX15EXBmBGloIt6teyLaPWWeMZMAY= 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=216.40.44.15 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 omf20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id 707FE1ADF4F; Fri, 9 Jan 2026 22:00:32 +0000 (UTC) Received: from [HIDDEN] (Authenticated sender: rostedt@goodmis.org) by omf20.hostedemail.com (Postfix) with ESMTPA id 2BCB320025; Fri, 9 Jan 2026 22:00:30 +0000 (UTC) Date: Fri, 9 Jan 2026 17:00:28 -0500 From: Steven Rostedt To: Alexei Starovoitov Cc: Mathieu Desnoyers , LKML , Linux trace kernel , bpf , Masami Hiramatsu , "Paul E. McKenney" , Sebastian Andrzej Siewior , Thomas Gleixner Subject: Re: [PATCH v5] tracing: Guard __DECLARE_TRACE() use of __DO_TRACE_CALL() with SRCU-fast Message-ID: <20260109170028.0068a14d@fedora> In-Reply-To: References: <20260108220550.2f6638f3@fedora> <20260109141930.6deb2a0a@gandalf.local.home> <3c0df437-f6e5-47c6-aed5-f4cc26fe627a@efficios.com> X-Mailer: Claws Mail 4.3.1 (GTK 3.24.51; x86_64-redhat-linux-gnu) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Rspamd-Server: rspamout07 X-Rspamd-Queue-Id: 2BCB320025 X-Stat-Signature: c8hexy5g764qqjqf97t3puc4p516gqgw X-Session-Marker: 726F737465647440676F6F646D69732E6F7267 X-Session-ID: U2FsdGVkX1/0vMYx7c3XI/LmL4WF94KqNRRrNen/jBA= X-HE-Tag: 1767996030-483354 X-HE-Meta: U2FsdGVkX1/xTqlTOKZD+wAifHP85oBj0PSnB+wau6oMw3Wt+2IAZtgcreEIrFpIdaUxQvLz07f0Xg/Hunz94oCKRrlseLp1xgrJSYVgzNuW7BbXCuHMJnuRUe46BB2xOs/6XO5SX7MxdrbsAMwAS8xFPIP/DERn54IfgR52H3wiA6cD+kgOWQKz0UT6VLF8qPG9kkppLLva7ajSS4wGnAbHq/XE8uslIF/mJBCKIMfZhdSj2MlHH/nPK+ErnzqofHO6EeoOF/8a0aCofO/yV1vD993lpn/h3KCHNi8esgQDT81WxvZCrwjQOPu6h01BLrPazzSe3+EG8cBm3eBtZs5rFsAyDfu6wBwES8Z9NiWsKwun9sjW3QDsGYctFfQSqH3QpxA6ibCbiJsIuRps3w== On Fri, 9 Jan 2026 13:54:34 -0800 Alexei Starovoitov wrote: > On Fri, Jan 9, 2026 at 12:21=E2=80=AFPM Mathieu Desnoyers > wrote: > > > > > > * preempt disable/enable pair: 1.1 = ns > > * srcu-fast lock/unlock: 1.5 = ns > > > > CONFIG_RCU_REF_SCALE_TEST=3Dy > > * migrate disable/enable pair: 3.0 = ns =20 >=20 > .. and you're arguing that 3ns vs 1ns difference is so important > for your out-of-tree tracer that in-tree tracers need to do > some workarounds?! wtf This has nothing to do with out of tree tracers. The overhead of the 22ns is for any tracepoint in an in-tree module. That's because the rq->nr_pinned isn't exported for modules to use. -- Steve