From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCHSET v2] io_uring IO interface Date: Fri, 11 Jan 2019 17:21:43 +0100 Message-ID: <20190111162143.GA14914@lst.de> References: <20190110024404.25372-1-axboe@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Roman Penyaev , Jens Axboe , linux-fsdevel , linux-aio@kvack.org, linux-block , linux-arch@vger.kernel.org, Christoph Hellwig , jmoyer@redhat.com, avi@scylladb.com, linux-block-owner@vger.kernel.org To: Ilya Dryomov Return-path: Content-Disposition: inline In-Reply-To: Sender: owner-linux-aio@kvack.org List-Id: linux-fsdevel.vger.kernel.org On Fri, Jan 11, 2019 at 05:11:57PM +0100, Ilya Dryomov wrote: > I think you can use the new IOCB_CMD_POLL from Christoph and avoid > epoll_wait() in favor of aio/io_uring interface, at least in new high > performance applications. Reaping events entirely in userspace (i.e. > performing io_getevents() without entering the kernel) has been > possible for a long time even with the existing aio interface. For io_uring we can reuse the IOCB_CMD_POLL concept, but we'd have to add a new cancel command, as the uring right now doesn't support cancelation. But I'd rather make that command a new opcode instead of a separate syscall, which would lead to a nicer design. A prototype for this should be fairly easy, I'd just want someone to actually use it for real life testing, like ScyllaDB does for IOCB_CMD_POLL. -- To unsubscribe, send a message with 'unsubscribe linux-aio' in the body to majordomo@kvack.org. For more info on Linux AIO, see: http://www.kvack.org/aio/ Don't email: aart@kvack.org 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 X-Spam-Level: X-Spam-Status: No, score=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8C483C43612 for ; Fri, 11 Jan 2019 16:21:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67CF12084C for ; Fri, 11 Jan 2019 16:21:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731478AbfAKQVq (ORCPT ); Fri, 11 Jan 2019 11:21:46 -0500 Received: from verein.lst.de ([213.95.11.211]:57024 "EHLO newverein.lst.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729961AbfAKQVq (ORCPT ); Fri, 11 Jan 2019 11:21:46 -0500 Received: by newverein.lst.de (Postfix, from userid 2407) id A8E3168DD2; Fri, 11 Jan 2019 17:21:43 +0100 (CET) Date: Fri, 11 Jan 2019 17:21:43 +0100 From: Christoph Hellwig To: Ilya Dryomov Cc: Roman Penyaev , Jens Axboe , linux-fsdevel , linux-aio@kvack.org, linux-block , linux-arch@vger.kernel.org, Christoph Hellwig , jmoyer@redhat.com, avi@scylladb.com, linux-block-owner@vger.kernel.org Subject: Re: [PATCHSET v2] io_uring IO interface Message-ID: <20190111162143.GA14914@lst.de> References: <20190110024404.25372-1-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org Message-ID: <20190111162143.yQI1dJDhL0Uj4GTq-AmEtdwyOnZsYAIH4ejvO_fQeSc@z> On Fri, Jan 11, 2019 at 05:11:57PM +0100, Ilya Dryomov wrote: > I think you can use the new IOCB_CMD_POLL from Christoph and avoid > epoll_wait() in favor of aio/io_uring interface, at least in new high > performance applications. Reaping events entirely in userspace (i.e. > performing io_getevents() without entering the kernel) has been > possible for a long time even with the existing aio interface. For io_uring we can reuse the IOCB_CMD_POLL concept, but we'd have to add a new cancel command, as the uring right now doesn't support cancelation. But I'd rather make that command a new opcode instead of a separate syscall, which would lead to a nicer design. A prototype for this should be fairly easy, I'd just want someone to actually use it for real life testing, like ScyllaDB does for IOCB_CMD_POLL.