From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) (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 DF3A5196C72; Thu, 6 Jun 2024 15:29:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=167.114.26.122 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717687757; cv=none; b=bSlZ+QtORlqDGeXap+J31IKFPPdiXFnwIaIf2BGX8PPUBhinS9SyZUzGKzJpo+kBdoIG1dK6EzjFcrEHzGA1YaegOh5vUC5PuWe9ppugC5dK5vQKPDk/1+Jt6YaFPtIoLv37YYTXFuH5zWGlgMWSF7d9y0OLyDfIhhj1exsuXj0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717687757; c=relaxed/simple; bh=eBB9aBsiHmO7WU3mW/9YuXTak8tCclcTkOS/Rq6E7qk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FgJhwY6lGBl9FQJU/UcnvMuKru/SMuGTSPV+919KhWFwYVnNRcwb4Q6hHqL0Z+UWSb8JBYYrKSLLid7NUA37wzrErGoMbnj4fZBWKItb5H2JtQ2TZzUQzUo8kHE05kQO1sMQGwyYHZuUjsbPXthK7xHi4YHWLXr8qMaGrKPdBKI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com; spf=pass smtp.mailfrom=efficios.com; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b=A3LjRNJB; arc=none smtp.client-ip=167.114.26.122 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=efficios.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=efficios.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=efficios.com header.i=@efficios.com header.b="A3LjRNJB" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=efficios.com; s=smtpout1; t=1717687754; bh=eBB9aBsiHmO7WU3mW/9YuXTak8tCclcTkOS/Rq6E7qk=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=A3LjRNJBEERCPjwPScg2ylCa5gji25832C322+S371TeZM/YKkxh0OPo7S/9Fc9jY QKmCofOGy8HweZsq1Mze1B/jrfqevddKdNyyVOXfYlIO/b9QDfVlD+2mJ6mUtF4+Ik pvjWsScyQtxDbtHGtimWQph+F70cAVEac222LcrSnRebRmWIysrodQR6BFhFwWZiHX h9cPNQ4pFk91vERkOaia81xFrhCpNZspEJR0sPuPvPJguln0WjehwQQrjJ7+9aI0Kj 2jLxTO9kmp+3igDS52Jn1sFxayMBry45PyVJ9W+gczgCQ6alF8fY5mC1cAhD7jycLL 4AUaPKpc6L9GQ== Received: from [172.16.0.134] (192-222-143-198.qc.cable.ebox.net [192.222.143.198]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4Vw7Xp3yhGz13B5; Thu, 6 Jun 2024 11:29:14 -0400 (EDT) Message-ID: <389a8c55-a169-47ef-99c0-48f58003b40c@efficios.com> Date: Thu, 6 Jun 2024 11:30:03 -0400 Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 3/3] rust: add tracepoint support To: Alice Ryhl , Steven Rostedt , Masami Hiramatsu , Peter Zijlstra , Josh Poimboeuf , Jason Baron , Ard Biesheuvel , Miguel Ojeda , Alex Gaynor , Wedson Almeida Filho , Boqun Feng , Gary Guo , =?UTF-8?Q?Bj=C3=B6rn_Roy_Baron?= , Benno Lossin , Andreas Hindborg Cc: linux-trace-kernel@vger.kernel.org, rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240606-tracepoint-v1-0-6551627bf51b@google.com> <20240606-tracepoint-v1-3-6551627bf51b@google.com> From: Mathieu Desnoyers Content-Language: en-US In-Reply-To: <20240606-tracepoint-v1-3-6551627bf51b@google.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 2024-06-06 11:05, Alice Ryhl wrote: > Make it possible to have Rust code call into tracepoints defined by C > code. It is still required that the tracepoint is declared in a C > header, and that this header is included in the input to bindgen. > > Signed-off-by: Alice Ryhl [...] > diff --git a/rust/helpers.c b/rust/helpers.c > index 2c37a0f5d7a8..0560cc2a512a 100644 > --- a/rust/helpers.c > +++ b/rust/helpers.c > @@ -165,6 +165,30 @@ rust_helper_krealloc(const void *objp, size_t new_size, gfp_t flags) > } > EXPORT_SYMBOL_GPL(rust_helper_krealloc); > > +void rust_helper_preempt_enable_notrace(void) > +{ > + preempt_enable_notrace(); > +} > +EXPORT_SYMBOL_GPL(rust_helper_preempt_enable_notrace); > + > +void rust_helper_preempt_disable_notrace(void) > +{ > + preempt_disable_notrace(); > +} > +EXPORT_SYMBOL_GPL(rust_helper_preempt_disable_notrace); > + > +bool rust_helper_current_cpu_online(void) > +{ > + return cpu_online(raw_smp_processor_id()); > +} > +EXPORT_SYMBOL_GPL(rust_helper_current_cpu_online); > + > +void *rust_helper___rcu_dereference_raw(void **p) > +{ > + return rcu_dereference_raw(p); > +} > +EXPORT_SYMBOL_GPL(rust_helper___rcu_dereference_raw); Ouch. Doing a function call for each of those small operations will have a rather large performance impact when tracing is active. If it is not possible to inline those in Rust, then implementing __DO_TRACE in a C function would at least allow Rust to only do a single call to C rather than go back and forth between Rust and C. What prevents inlining those helpers in Rust ? Thanks, Mathieu -- Mathieu Desnoyers EfficiOS Inc. https://www.efficios.com