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=-8.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 42B4BC18E7D for ; Wed, 22 May 2019 09:22:28 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 1173D2075B for ; Wed, 22 May 2019 09:22:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1173D2075B Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Received: from localhost ([127.0.0.1]:39065 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hTNS7-0008CV-8R for qemu-devel@archiver.kernel.org; Wed, 22 May 2019 05:22:27 -0400 Received: from eggs.gnu.org ([209.51.188.92]:41994) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hTNMJ-0004by-V1 for qemu-devel@nongnu.org; Wed, 22 May 2019 05:16:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hTNMI-0001BN-PA for qemu-devel@nongnu.org; Wed, 22 May 2019 05:16:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:42842) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hTNMF-000187-Uh; Wed, 22 May 2019 05:16:24 -0400 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 3012A3058838; Wed, 22 May 2019 09:16:18 +0000 (UTC) Received: from localhost.localdomain (ovpn-117-92.ams2.redhat.com [10.36.117.92]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 06448604D7; Wed, 22 May 2019 09:16:12 +0000 (UTC) Date: Wed, 22 May 2019 11:16:11 +0200 From: Kevin Wolf To: Aarushi Mehta Message-ID: <20190522091611.GA6087@localhost.localdomain> References: <20190521235215.31341-1-mehta.aaru20@gmail.com> <20190521235215.31341-2-mehta.aaru20@gmail.com> <1c277edc76e47fbbaae0ecdd6774e24ac9a94ee5.camel@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1c277edc76e47fbbaae0ecdd6774e24ac9a94ee5.camel@gmail.com> User-Agent: Mutt/1.11.3 (2019-02-01) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.41]); Wed, 22 May 2019 09:16:23 +0000 (UTC) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 209.132.183.28 Subject: Re: [Qemu-devel] [Qemu-block] [RFC PATCH 1/9] qapi/block-core: add option for io_uring X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: qemu-block@nongnu.org, qemu-devel@nongnu.org, saket.sinha89@gmail.com, Stefan Hajnoczi , Julia Suvorova Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Am 22.05.2019 um 02:51 hat Aarushi Mehta geschrieben: > On Tue, 2019-05-21 at 19:39 -0500, Eric Blake wrote: > > On 5/21/19 6:52 PM, Aarushi Mehta wrote: > > > Signed-off-by: Aarushi Mehta > > > > Sparse on the details. The subject line says what, but without a > > 'why' > > for how io_uring is different from existing aio options, it's hard to > > see why I'd want to use it. Do you have any benchmark numbers? > > For peak performance, io_uring helps us get to 1.7M 4k IOPS with > polling. aio reaches a performance cliff much lower than that, at 608K. > If we disable polling, io_uring is able to drive about 1.2M IOPS for > the (otherwise) same test case. > > More details, and the source for the above is at > http://kernel.dk/io_uring.pdf > > > > --- > > > qapi/block-core.json | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/qapi/block-core.json b/qapi/block-core.json > > > index 7ccbfff9d0..116995810a 100644 > > > --- a/qapi/block-core.json > > > +++ b/qapi/block-core.json > > > @@ -2776,11 +2776,12 @@ > > > # > > > # @threads: Use qemu's thread pool > > > # @native: Use native AIO backend (only Linux and Windows) > > > +# @io_uring: Use linux io_uring > > > > Missing a '(since 4.1)' tag. > > > > > # > > > # Since: 2.9 > > > ## > > > { 'enum': 'BlockdevAioOptions', > > > - 'data': [ 'threads', 'native' ] } > > > + 'data': [ 'threads', 'native','io_uring' ] } > > > > Missing space after ',' (not essential, but matching style is nice). > > Should the new element be defined conditionally, so that > > introspection > > only sees the new enum member when compiled for Linux? > > > I'm not sure what would be the benefits of that? We already check for > Linux at configure, and this would reduce readability. We aren't doing > this for native. BlockdevAioOptions is used in BlockdevOptionsFile, which contains the options for two different drivers: file-posix and file-win32. Both of them support both 'threads' and 'native'. However, I don't think you'll add the new mode to the Windows driver. So I think making it conditional on CONFIG_POSIX at least is necessary. Kevin