Received: from malur.postgresql.org ([217.196.149.56]) by arkaria.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1rdbI3-006SCQ-C8 for pgsql-hackers@arkaria.postgresql.org; Fri, 23 Feb 2024 19:32:59 +0000 Received: from localhost ([127.0.0.1] helo=malur.postgresql.org) by malur.postgresql.org with esmtp (Exim 4.94.2) (envelope-from ) id 1rdbI0-002g3l-0t for pgsql-hackers@arkaria.postgresql.org; Fri, 23 Feb 2024 19:32:56 +0000 Received: from magus.postgresql.org ([2a02:c0:301:0:ffff::29]) by malur.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1rdbHz-002g3d-Lo for pgsql-hackers@lists.postgresql.org; Fri, 23 Feb 2024 19:32:56 +0000 Received: from mail-io1-xd29.google.com ([2607:f8b0:4864:20::d29]) by magus.postgresql.org with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256 (Exim 4.94.2) (envelope-from ) id 1rdbHv-000ZM7-Bm for pgsql-hackers@postgresql.org; Fri, 23 Feb 2024 19:32:55 +0000 Received: by mail-io1-xd29.google.com with SMTP id ca18e2360f4ac-7c785dda899so49539739f.2 for ; Fri, 23 Feb 2024 11:32:51 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1708716769; x=1709321569; darn=postgresql.org; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:from:to:cc:subject:date:message-id:reply-to; bh=yBebfQlFra5+QkZy54FZejyY5iAioYuU630caXslXY0=; b=B8pOadCyI2EjDv5QdhsFovDrxRMZ0AIO44POCsDo/GlMTlniDusQ6/P/8P+skKY0uw LkrfO+zqhiThbglBT8dZsiviRUW67yC1vv9aDlWaGwqT8sqdG1m/O5Ir5KTt+QJZk90n 3v2+Nkkjh8UMplMmfT5dU9qP58XD5W4GFw038K/HOolmpssxvfo2iPWaRSjG8kjNq+7j gE2hbjWWJMP21M0L/MneSQOwbS5rb69/Cpu8l6tef8AT7VBW/QqEIj4Ki3t+yS/D1Ojq idGQv8sBUVXVYag3hVR+w9rGr0jJTqZbgqAsNHiBqi2G9mQ67n3fwtXGeZ9sH9t5Kpt2 Q/Cw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1708716769; x=1709321569; h=in-reply-to:content-disposition:mime-version:references:message-id :subject:cc:to:from:date:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=yBebfQlFra5+QkZy54FZejyY5iAioYuU630caXslXY0=; b=b8BqHxf3zQ643v/XSqjkx+kfcWc07pPvVlZ9xrRpO26oLf3aXqDeen92ToyFuThLVH boT9cwxt9YJjEY12TTgEB+6ltxdSJt/jWy4tJawGFHVJDUM4J0BR+31HlPxN25mS4q0J 3GI58tWhl9OmiHy79iHa13ykYlz6rP44Rg1BTOIlosGLAEGaMov/vO4TPh/aIXuaQlqL B+CTIlDCNoDdxmcVr7cQMA/fEWWk7ewXmtzgiMYW97X2aYbccJ1z0HoJ+vCJThG7sxU/ hFAXi/CAQ0Trwm3HQrGtFy5cpwqXjB8I8GVM3NebYI8Xnej9ouOE+teAZ+i3zZuGpgBM VbyQ== X-Forwarded-Encrypted: i=1; AJvYcCXmORMvQ7HjdX4CQ92BGceKZ4zn3ZflU4iDR130E3tYha7aLT1NQe9LMxmp66ElZG4ImcE7qZxs0PnJVuq/YRiIcURV2vQAcUsNBCA0 X-Gm-Message-State: AOJu0Yy6v6plnIi5o5Aoz23GFPZwCtSdQvCJMxARMi6Kn9oFEg0ASlHw TvJmti0th+7zID8h2/XFJK6WHC+CWiEt418zhyjJ0B9WE1V5h9oXAQy4k59l X-Google-Smtp-Source: AGHT+IGKp2hShGic796o3sN7bgjAoGOQ6hAV5TTDxemZQ5qU5zBm7VgrFFEfY1L3kfKR6BbXVgIyuQ== X-Received: by 2002:a05:6602:276d:b0:7c4:4274:9c39 with SMTP id l13-20020a056602276d00b007c442749c39mr939099ioe.14.1708716769618; Fri, 23 Feb 2024 11:32:49 -0800 (PST) Received: from nathanxps13 (162-195-168-172.lightspeed.stlsmo.sbcglobal.net. [162.195.168.172]) by smtp.gmail.com with ESMTPSA id b23-20020a02c997000000b004740cbc2688sm3922414jap.14.2024.02.23.11.32.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 23 Feb 2024 11:32:49 -0800 (PST) Date: Fri, 23 Feb 2024 13:32:47 -0600 From: Nathan Bossart To: Jeff Davis Cc: Bharath Rupireddy , Andres Freund , pgsql-hackers@postgresql.org Subject: Re: locked reads for atomics Message-ID: <20240223193247.GA1698856@nathanxps13> References: <20231110205128.GB1315705@nathanxps13> <20231110231150.fjm77gup2i7xu6hc@alap3.anarazel.de> <20231111023813.GB1408159@nathanxps13> <20231111024839.op2d2id33x777mll@alap3.anarazel.de> <20231111025529.GA1409540@nathanxps13> <20231127210030.GA140335@nathanxps13> <20240223161758.GA1697194@nathanxps13> <274e5925684e71b0df4f7c0f473b8ce6fc6c382b.camel@j-davis.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <274e5925684e71b0df4f7c0f473b8ce6fc6c382b.camel@j-davis.com> List-Id: List-Help: List-Subscribe: List-Post: List-Owner: List-Archive: Archived-At: Precedence: bulk On Fri, Feb 23, 2024 at 10:25:00AM -0800, Jeff Davis wrote: > To be clear: > > x = pg_atomic_[read|write]_membarrier_u64(&v); > > is semantically equivalent to: > > pg_memory_barrier(); > x = pg_atomic_[read|write]_u64(&v); > pg_memory_barrier(); > > ? > > If so, that does seem more convenient. I think that's about right. The upthread feedback from Andres [0] provides some additional context. [0] https://postgr.es/m/20231110231150.fjm77gup2i7xu6hc%40alap3.anarazel.de -- Nathan Bossart Amazon Web Services: https://aws.amazon.com