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 3E8E6C433F5 for ; Wed, 25 May 2022 00:56:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233416AbiEYA4R (ORCPT ); Tue, 24 May 2022 20:56:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48636 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241884AbiEYA4Q (ORCPT ); Tue, 24 May 2022 20:56:16 -0400 Received: from mail-oa1-x2b.google.com (mail-oa1-x2b.google.com [IPv6:2001:4860:4864:20::2b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 967C912614 for ; Tue, 24 May 2022 17:56:14 -0700 (PDT) Received: by mail-oa1-x2b.google.com with SMTP id 586e51a60fabf-f189b07f57so24374896fac.1 for ; Tue, 24 May 2022 17:56:14 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=mime-version:from:date:message-id:subject:to; bh=/ieTAqAN4d6hKkMcFOVhLy+tMDLYmgD/2JoqYo9l0OQ=; b=lZRPuImSeNfBlYcP0gavDmJudzDyZoOXZYkqnYW8YoALi1oe1WYFuz4t4wemrwLtIX VX9ikgn7X/S4b/tnO+A2w0ym21bGzdhKAFqq6Jn+XEX4D2LOt2Zcjle1IH731+fXOEwb D372uzhS7cILZE9FVYmCL6MfVdCk9eYYLPf2htz0e2o8YicwU56Cw5mcSFqqygvzov4o VNcQgorns8FfikdXPYwUBqvUQ0gcuJnS+v7U19Uhsu6vhJyEHiCSNO4s7PNHjhwf5yGt FxoDToQT6mh/bZw4daxUNNK1u6I6zotpWUCkncFeY6XdZ1TCuCEuYJX39sh1Vc+CTcVO gpdA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:from:date:message-id:subject:to; bh=/ieTAqAN4d6hKkMcFOVhLy+tMDLYmgD/2JoqYo9l0OQ=; b=ZEXS1ypFfSZZWSIc4UWi9g8BWoK+XP7VvUWG/bdWkYlpQAZxHJvMrzpNz89mD2vplM qdjtd51n+nQjne1rVnXYw4mt6lgcBss2wC4o3u2odrrfXTuJo+99W8Q2V+yahikDELSi 7JV3nZfWz0hvKRRAEjq04tqJnhzNxOTl6IF4b9I+Y5C4zv7hr8VsPzQia+gqM2A4A3Q7 fJtKtU3naq7s8X2tw2G8Fd40tWhygADrBz1qeYqE3ttr3w+r4tXwYd0h1KbxnccOVkFg 92mXAVMXF9jAoyzXvNNW9xt6H7Rwnw9QSxg9yrawtDJCB6S4CR/1oa3V3FxN0uVaYNYa p83A== X-Gm-Message-State: AOAM531MG85Jt7yvXJxfVC5yV69S8JyeUCTiIoKWw7adLiHccN/3AEXm WCUJHyVeI0lcg1n6S879TBWqwITHt2pZQSnQzLXtWsbe X-Google-Smtp-Source: ABdhPJwlp4gdlJxhS14y9/yJxnLfs0uqU5ZSvGof9aeIUYBtB7QQ84NwMrcGk83nqTjG1P0cl73yeP0swzFSKznZQDI= X-Received: by 2002:a05:6870:f699:b0:f1:de44:9f5b with SMTP id el25-20020a056870f69900b000f1de449f5bmr4106788oab.284.1653440173627; Tue, 24 May 2022 17:56:13 -0700 (PDT) MIME-Version: 1.0 From: Changman Lee Date: Wed, 25 May 2022 09:56:02 +0900 Message-ID: Subject: io uring support for character device To: io-uring@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Hi List, I'm CM Lee. I'm developing a custom character device managing pcie dma. I've tried to use io uring for the char device which supports readv and writev with synchronous and blocking manner and seek. When I use a io uring with IORING_SETUP_IOPOLL and IORING_SETUP_SQPOLL for reducing syscall overhead, a readv of the char device driver seems to be not called. So I added a_ops->direct_IO when the device is opened with O_DIRECT. But the result was the same. This is my question. Q1: Does io uring support a character device ? Q2: Is it better to reimplement a device driver as block device type ? Thanks, CM