From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 4EE2DC433F5 for ; Wed, 9 Mar 2022 23:49:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235703AbiCIXuL (ORCPT ); Wed, 9 Mar 2022 18:50:11 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46762 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235362AbiCIXuL (ORCPT ); Wed, 9 Mar 2022 18:50:11 -0500 Received: from mail-lf1-x133.google.com (mail-lf1-x133.google.com [IPv6:2a00:1450:4864:20::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2D5FD11C7C4 for ; Wed, 9 Mar 2022 15:49:11 -0800 (PST) Received: by mail-lf1-x133.google.com with SMTP id s25so6511228lfs.10 for ; Wed, 09 Mar 2022 15:49:11 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=message-id:date:mime-version:user-agent:content-language:to:from :subject:content-transfer-encoding; bh=eaMRnJWRZaMycUZdpvL5QLW+AGCkesCF7E8MDz4o5Bk=; b=RtnEWQPn11LLP5NdJOCZLj8rwOEiy1m5Ft4PpSaRyXoCy8yjiE2tCvsSThRL5GYs7K ROtAv7/chky+LKyO46gYUbtGesHK1tLyuwFQr40apPlAHw9+Ob2/MrPcccc3rVYpkl1P lEZsBtpcx3zF7IFPLRiO/rSsIMMNgC0Tt5GfIJtOGw5U3r4RW7Zjbfcd0bIi0iGzBMI4 mD8I8URRQUuMmJt1cDMX4hPvF2n5CJrt7u6e7YMEK7uB4OvvroufsEz97CUJ7YnwtL2L ZDQeKadtmcDRdFAkpObvRbIacKVTv8gDzbD9Oz6clHpgpoHnFeO6UFCJs5RdJ3P4mJGH PC8g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:message-id:date:mime-version:user-agent :content-language:to:from:subject:content-transfer-encoding; bh=eaMRnJWRZaMycUZdpvL5QLW+AGCkesCF7E8MDz4o5Bk=; b=XOx5ZKIuJqBjq3aVxlTCQfsvdLjj1fUnJmnaIwxdRCYYdxM4iktDl01Zh+BOmB18T6 zrwIbxmDG+y0eiiZRfWhfyY6FNYkdSxHuLfBmkVnEQJpAI2EUCym+3tMXHstjNy+Or/9 n7adUkATr8qEJWWsC5XV5L5PLmwllhzecvGkHnx9ltUipj+XU4pigQYDlwnturdXCPyW 5RnZY4b0eGtsmd57lxhFIVkNFKfmdVVqgIKylsC3KRbuOOg6PYyc/Pt5pj3tIGGK8vly 5pwupgfkXp+BpoQ3TdJi1GI8MV6qvDUBBToYpQKvPYDBoT+8iljuOxovpcSMPR/neWWP 7k3g== X-Gm-Message-State: AOAM531ymzfyUWaopSAiooSSCOEy2FYIQ0FTUjc7xVydmNVchPZbN54n wZXE+z9+qiu8OEZObEQV/qw9r2wTKA== X-Google-Smtp-Source: ABdhPJw9b/cbgyYslRZH1yVPBNlKFtMB6xwdR/biSh92o+mkyKBzTuDeG+2UCYW9jc2JOoi+KdsM6A== X-Received: by 2002:a19:f80c:0:b0:448:26dc:4f8b with SMTP id a12-20020a19f80c000000b0044826dc4f8bmr1320170lff.25.1646869749218; Wed, 09 Mar 2022 15:49:09 -0800 (PST) Received: from [192.168.1.140] ([217.117.243.16]) by smtp.gmail.com with ESMTPSA id bt23-20020a056512261700b0044400161095sm647577lfb.168.2022.03.09.15.49.07 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 09 Mar 2022 15:49:08 -0800 (PST) Message-ID: Date: Thu, 10 Mar 2022 02:49:06 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Content-Language: en-US To: io-uring@vger.kernel.org From: Artyom Pavlov Subject: Sending CQE to a different ring Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Greetings! A common approach for multi-threaded servers is to have a number of threads equal to a number of cores and launch a separate ring in each one. AFAIK currently if we want to send an event to a different ring, we have to write-lock this ring, create SQE, and update the index ring. Alternatively, we could use some kind of user-space message passing. Such approaches are somewhat inefficient and I think it can be solved elegantly by updating the io_uring_sqe type to allow accepting fd of a ring to which CQE must be sent by kernel. It can be done by introducing an IOSQE_ flag and using one of currently unused padding u64s. Such feature could be useful for load balancing and message passing between threads which would ride on top of io-uring, i.e. you could send NOP with user_data pointing to a message payload. Best regards, Artyom Pavlov.