From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from simark.ca by simark.ca with LMTP id 83hXAMamlGREFQsAWB0awg (envelope-from ) for ; Thu, 22 Jun 2023 15:53:42 -0400 Authentication-Results: simark.ca; dkim=pass (2048-bit key; unprotected) header.d=lists.lttng.org header.i=@lists.lttng.org header.a=rsa-sha256 header.s=default header.b=aeusp3mG; dkim-atps=neutral Received: by simark.ca (Postfix, from userid 112) id E68531E0BB; Thu, 22 Jun 2023 15:53:41 -0400 (EDT) Received: from lists.lttng.org (lists.lttng.org [167.114.26.123]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by simark.ca (Postfix) with ESMTPS id 7D6E21E0AC for ; Thu, 22 Jun 2023 15:53:39 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.lttng.org; s=default; t=1687463619; bh=3KCRPBEZdE+LCAtLgIPMWiXski8DhD/X8eGBwSVvvZs=; h=To:Cc:In-Reply-To:References:Date:Subject:List-Id: List-Unsubscribe:List-Archive:List-Post:List-Help:List-Subscribe: From:Reply-To:From; b=aeusp3mGQB+CV2XpvGtz34IJaUFvUBYDrpqGL5vGIs0N6CC3J+OLNhRw+NwPaplA6 re7omVPufHuGEhCcVlxuxplqcBAA/j6eWpu6qz6gKbOi/6LhC0dB3bKMtKJdTMtp8Q obKJJJfgFr5obM+PHEfuSBOaBqJzB26bjGiD4/Y4gwhc6H7qix7ed69RFzmCVo6Gjx eOQIN5k47QkkjhBMygqwa1MIUIsmvm/nH7nr9Eyki3ZaU7youlRUqwNPhL0TCA0Rz/ YjFc0BC714YXkFT+ND7O5tqKPJDm8xDkiJZnn8fUEY26dr65UR4T6hj1WU8hZ1sQ6J yMs5IEpaQTGFQ== Received: from lists-lttng01.efficios.com (localhost [IPv6:::1]) by lists.lttng.org (Postfix) with ESMTP id 4Qn9zQ6x5wz200k; Thu, 22 Jun 2023 15:53:38 -0400 (EDT) Received: from smtpout.efficios.com (smtpout.efficios.com [167.114.26.122]) by lists.lttng.org (Postfix) with ESMTPS id 4Qn9zM3xHsz200j for ; Thu, 22 Jun 2023 15:53:35 -0400 (EDT) Received: from localhost (modemcable094.169-200-24.mc.videotron.ca [24.200.169.94]) by smtpout.efficios.com (Postfix) with ESMTPSA id 4Qn9zL1KVFz19FR; Thu, 22 Jun 2023 15:53:34 -0400 (EDT) To: paulmck@kernel.org, Mathieu Desnoyers Cc: lttng-dev@lists.lttng.org In-Reply-To: <105bad2a-9fed-4353-a434-a571ce9da7ac@paulmck-laptop> Organization: EfficiOS References: <20230515201718.9809-1-odion@efficios.com> <20230515201718.9809-3-odion@efficios.com> <105bad2a-9fed-4353-a434-a571ce9da7ac@paulmck-laptop> Date: Thu, 22 Jun 2023 15:53:33 -0400 Message-ID: <87zg4rl1du.fsf@laura> MIME-Version: 1.0 Subject: Re: [lttng-dev] [PATCH 02/11] urcu/uatomic: Use atomic builtins if configured X-BeenThere: lttng-dev@lists.lttng.org X-Mailman-Version: 2.1.39 Precedence: list List-Id: LTTng development list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , From: Olivier Dion via lttng-dev Reply-To: Olivier Dion Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: lttng-dev-bounces@lists.lttng.org Sender: "lttng-dev" On Thu, 22 Jun 2023, "Paul E. McKenney" wrote: > I suggest C11 volatile atomic load/store. Load/store fusing is permitted > for non-volatile atomic loads and stores, and such fusing can ruin your > code's entire day. ;-) Good catch. Seems like not a problem on GCC (yet), but Clang is extremely aggressive and seems to do store fusing on some corner cases [0]. However, I do not find any simple reproducer of load/store fusing. Do you have example of such fusing, or is this a precaution? In the meantime, back to reading the standard to be certain :-) [0] https://godbolt.org/z/odKG9a75a -- Olivier Dion EfficiOS Inc. https://www.efficios.com _______________________________________________ lttng-dev mailing list lttng-dev@lists.lttng.org https://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev