From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-189.mta0.migadu.com (out-189.mta0.migadu.com [91.218.175.189]) (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 6EC1132C8B for ; Sun, 16 Mar 2025 17:12:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.189 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742145157; cv=none; b=LV0ZdOCJFwN7YYozc3pm7/o4yLLpSGlXhF9n2vcax/TkPlME57A4WabaAXPsLSGdf0GQdBPBvCUQKXjHHi2ShQxc2tSyBKa7ZHD/zidKRKhMEAQDmB5A5dxRrBM0RF7Z0K7LXcG7CioPIrgU34ZCKQjgviK1x5gxSc52EgDGayY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1742145157; c=relaxed/simple; bh=C59jo72SXsAxUcrZg8lBX0LaXT2e3dZdZm89dpH2W8M=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=maDBG0Fh9GMbfmQVHG8NiwCBjpmLJfL6KzKvAsqIViic+nSBGlAEgPv59T/P7yhNI9VxOHfuMReXb9K7XBAmuCFLSnrwbngyCcCAjqqa4e8+8Itjy9A8Q9BNgNDa+idV3mBmIPPdrrIU04dVv+91hThjjUJXz3CVKEoqd9r7+0c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=iencinas.com; spf=pass smtp.mailfrom=iencinas.com; dkim=pass (2048-bit key) header.d=iencinas.com header.i=@iencinas.com header.b=NYPBl0uX; arc=none smtp.client-ip=91.218.175.189 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=iencinas.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=iencinas.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=iencinas.com header.i=@iencinas.com header.b="NYPBl0uX" Message-ID: <03f234c4-faac-49ef-8956-2bf04579eab7@iencinas.com> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=iencinas.com; s=key1; t=1742145152; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:autocrypt:autocrypt; bh=XI7icQNNvgcHDJdFHkdIrklFm0qlpl4UpJNVMY8AnGY=; b=NYPBl0uXK45r5/OWgxlGPaqqJVUSWQwRegOhx+cbDcrimZc5PKH+uE1F+CKuajaXgacmdY IXUvF4CbbxJ3zLHtB+inPA27hwmUlG6LSL/TbDE/UV5gY4YzGvtytb5oyOZlMiwT6CjgyA BIrh1G9IvFE9Y4/ONMoP+RjHkkZ/L7eT5lIYtnyPXkPpxKHgecLw2PkPK466e3S1LBIyrI isOLqPcivPFHDKqCvT+fn6J+geCbXYiJan2nnZgJEaaw2v22s9TUG3c8Q/MUnn+uoEQd43 JxXkha59tCCumywX9sopz7ppd+dF6yM0FRlVCDZn0saI3yNNTVuZsyXp+YD9+w== Date: Sun, 16 Mar 2025 18:12:29 +0100 Precedence: bulk X-Mailing-List: perfbook@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: Is Alpha non-other-multicopy atomic? To: Akira Yokosawa Cc: perfbook@vger.kernel.org, "Paul E. McKenney" References: <6c2c3199-e092-4909-853e-4fad1ca0f35c@iencinas.com> <64509d29-0593-4b7b-bb29-8a96835ac1bc@gmail.com> Content-Language: en-US X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Ignacio Encinas Rubio Autocrypt: addr=ignacio@iencinas.com; keydata= xjMEZgaZEBYJKwYBBAHaRw8BAQdAYZxeXU5yoeLYkQpvN+eE3wmAF4V0JUzIlpm/DqiSeBnN LElnbmFjaW8gRW5jaW5hcyBSdWJpbyA8aWduYWNpb0BpZW5jaW5hcy5jb20+wo8EExYIADcW IQSXV5vKYfM26lUMmYnH3J3Ka8TsNgUCZgaZEAUJBaOagAIbAwQLCQgHBRUICQoLBRYCAwEA AAoJEMfcncprxOw21F4BAJe+mYh3sIdSvydyDdDXLFqtVkzrFB8PVNSU9eZpvM0mAP9996LA N0gyY7Obnc3y59r9jOElOn/5fz5mOEU3nE5lCc44BGYGmRESCisGAQQBl1UBBQEBB0CVC5o6 qnsTzmmtKY1UWa/GJE53dV/3UPJpZu42p/F0OAMBCAfCfgQYFggAJhYhBJdXm8ph8zbqVQyZ icfcncprxOw2BQJmBpkRBQkFo5qAAhsMAAoJEMfcncprxOw2N8ABAPcrkHouJPn2N8HcsL4S SVgqxNLVOpsMX9kAYgIMqM0WAQCA40v0iYH1q7QHa2IfgkrBzX2ZLdXdwoxfUr8EY5vtAg== In-Reply-To: <64509d29-0593-4b7b-bb29-8a96835ac1bc@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 16/3/25 12:37, Akira Yokosawa wrote: > As is well known, Alpha is infamous of its lack of address-dependency > guarantees. I don't see much point in discussing whether it is multicopy > atomic or not. I agree this is not particularly important, I just found contradicting information and wanted to clarify/fix Table 15.5. > If you have access to an Alpha machine with 3 or more CPUs, > you should be able to run this test with the help of klitmus7. Thanks for the test. Sadly, I don't have access to an Alpha CPU (I was born after DEC was bought by Compaq) > Finally, my mental model of other-multi-copy might be different from > those defined in papers you cited below. Might be, I have just realized mine is wrong. I have just run Listing 15.16 (C-WRC...) in herd using the "linux" model to realize the exists clause can trigger. Note that it can do so while "RFE" imposes order for the "linux" model (it is part of happens-before), so my original comment stating non-mca == rfe does not impose order is wrong if Read[X = 0] (fr) -> Write[X = 1] does not mean that the read is ordered before the write. However, this doesn't seem to be the case for Alpha [3] Section 5.6.1.2: The ordering relation Before (<=) is acyclic Section 5.6.1.4: If u and v are overlapping read/write accesses, at least one of which is a write, then u and v must be comparable in the BEFORE (<=) ordering, that is, either u <= v or v <= u. It's still my opinion that Alpha is other-multi-copy atomic but I understand it is a bit pointless to discuss about this... Sorry, I couldn't resist. Thanks [3] https://download.majix.org/dec/alpha_arch_ref.pdf