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 E8F2DC433FE for ; Wed, 13 Apr 2022 10:33:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230235AbiDMKfb (ORCPT ); Wed, 13 Apr 2022 06:35:31 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55568 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231791AbiDMKfa (ORCPT ); Wed, 13 Apr 2022 06:35:30 -0400 Received: from mail-ej1-x62f.google.com (mail-ej1-x62f.google.com [IPv6:2a00:1450:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9FBFE33A14 for ; Wed, 13 Apr 2022 03:33:09 -0700 (PDT) Received: by mail-ej1-x62f.google.com with SMTP id s18so3111423ejr.0 for ; Wed, 13 Apr 2022 03:33:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=scylladb-com.20210112.gappssmtp.com; s=20210112; h=message-id:date:mime-version:user-agent:content-language:to:from :subject:organization:content-transfer-encoding; bh=FD3EvitDeQpOOlN1vK/20FkCoZM0dxElDZkI93Joh2U=; b=GC1/KWjSUA3j+bbLueArTsWoaTVYj3pRBtNuogWvthm5EnOVAcccnR12lTWB5L8Pfc MlTeaLlXNeREfp3tzV3QJvgfAm+X92QoIiVOey0uPtgWDB9BD42tlekHEu9QFHxmK6o5 QpsofyTCGP7ni/tEI9qnB8UvyD+niMuJ+2FoeqbVTnF14adymEGcOoWDnH7l1RxH9S7x J8Ay3CZKtUgvg4Ro8r1npZaJb/p8TdUC88Vt6Fk5rJWBWuWOg0vlzi3yGtkkWDdjXGcH Q0Np3iivQdQQKMNF2XmCK6anY/SXAifU74lSXxT2MK1izV8941B+9/cwXME45kx7yb6Y I+WQ== 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:organization :content-transfer-encoding; bh=FD3EvitDeQpOOlN1vK/20FkCoZM0dxElDZkI93Joh2U=; b=0VmPRQraY9E3owTxHAPDKIMYgfgJJKufYw681uTiluJMXkyw6A7MBkc/xY0Ibwg6zZ 758ZbG2BkQvUZ3KynJ4LNJgLg8r5JVj90ZUhGIWCFs/5TM94NhmHuVw6i9YZ5UsR5i1k tuKll6WKcJteqP69fStsB8aNIvErwZeCN0ZAQ6Kvpd24Biid0XpEXaT9OdCxoVei7M4a HNohKGIINqVNDrJ7+jrKwky+OG466ZMEh6NNefBopMQTELGN5yfvg3At04CFP2N0Xnvp WlbCWSE6nB4Y8+f4tKdDDoUBKU2DwpyBRnWC1QIKufR5HaFgc9FsP6ezV0RGJCaz8lx5 8uJA== X-Gm-Message-State: AOAM530f/2yj/RHf1Rs1X/4iTht2UpkQvB9n4FkcbVk8py7beAftHm4W BZZ+bT7Go8uSlQrZJtDM2O5RUvqaK9j5zQ== X-Google-Smtp-Source: ABdhPJzdWG3pRlINpq+SRXikAinvYT20+XTNB1zSuwUgBYGCSMThQ8+tAOlR3c0FrB+5GxAc1qoZnA== X-Received: by 2002:a17:906:4783:b0:6d0:9b6e:b5a5 with SMTP id cw3-20020a170906478300b006d09b6eb5a5mr39537486ejc.526.1649845987954; Wed, 13 Apr 2022 03:33:07 -0700 (PDT) Received: from [10.0.0.1] (system.cloudius-systems.com. [199.203.229.89]) by smtp.gmail.com with ESMTPSA id f7-20020a0564021e8700b0041d03a94f27sm1014130edf.66.2022.04.13.03.33.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 13 Apr 2022 03:33:06 -0700 (PDT) Message-ID: Date: Wed, 13 Apr 2022 13:33:05 +0300 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.7.0 Content-Language: en-US To: io-uring@vger.kernel.org From: Avi Kivity Subject: memory access op ideas Organization: ScyllaDB 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 Unfortunately, only ideas, no patches. But at least the first seems very easy. - IORING_OP_MEMCPY_IMMEDIATE - copy some payload included in the op itself (1-8 bytes) to a user memory location specified by the op. Linked to another op, this can generate an in-memory notification useful for busy-waiters or the UMWAIT instruction This would be useful for Seastar, which looks at a timer-managed memory location to check when to break computation loops. - IORING_OP_MEMCPY - asynchronously copy memory Some CPUs include a DMA engine, and io_uring is a perfect interface to exercise it. It may be difficult to find space for two iovecs though.