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 2CE9DC6FD18 for ; Wed, 29 Mar 2023 16:11:43 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229452AbjC2QLm (ORCPT ); Wed, 29 Mar 2023 12:11:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51744 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229555AbjC2QLk (ORCPT ); Wed, 29 Mar 2023 12:11:40 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 300B45B86 for ; Wed, 29 Mar 2023 09:11:22 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 614EA61D9A for ; Wed, 29 Mar 2023 16:11:10 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 08632C433EF; Wed, 29 Mar 2023 16:11:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1680106269; bh=9DcUxntLnab5cJ/+8zw/KFyM3GJUThn6mt1RVFym3OI=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=BtX1GYrz6I3x76GBwPYUCSl7Yy75ev4djW4jtGV4pHaxqr3LLYGR3bbSAqz807zVr CwpfFioDelLfPz2SMrHlcoDzGEiTfZ3kv3NusnwkudId1FTIXZEsDNOhiZqmILEUdz /a3EwveV9Ukq9wPy9eUKQnlamQv9jNs7wqT8hLmQ6YHehZLeAo8oz098VGQoJiay8+ vl5KYtZAVeR7SY/trbx3XTrdiu21/jb3v/Cgk5mo+5tE2CJFWX0k+8UexkoNAVFN5P WtZCtQjnnahO6OtSOVA7+HxVORaESzwZhsVOxNSXvXNBNp5Z+jFZJhAR3pVsC3/8AL RoV0XHd91IuWQ== Date: Wed, 29 Mar 2023 10:11:06 -0600 From: Keith Busch To: Kanchan Joshi Cc: Kanchan Joshi , Keith Busch , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, axboe@kernel.dk, hch@lst.de Subject: Re: [PATCH 2/2] nvme: use blk-mq polling for uring commands Message-ID: References: <20230324212803.1837554-1-kbusch@meta.com> <20230324212803.1837554-2-kbusch@meta.com> <20230327135810.GA8405@green5> <20230328074939.GA2800@green5> <20230329084618.GB2800@green5> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230329084618.GB2800@green5> Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On Wed, Mar 29, 2023 at 02:16:18PM +0530, Kanchan Joshi wrote: > On Tue, Mar 28, 2023 at 08:52:53AM -0600, Keith Busch wrote: > > > > + else if (issue_flags & IO_URING_F_IOPOLL) > > > > + ioucmd->flags |= IORING_URING_CMD_NOPOLL; > > > > > > If IO_URING_F_IOPOLL would have come here as part of "ioucmd->flags", we > > > could have just cleared that here. That would avoid the need of NOPOLL flag. > > > That said, I don't feel strongly about new flag too. You decide. > > > > IO_URING_F_IOPOLL, while named in an enum that sounds suspiciouly like it is > > part of ioucmd->flags, is actually ctx flags, so a little confusing. And we > > need to be a litle careful here: the existing ioucmd->flags is used with uapi > > flags. > > Indeed. If this is getting crufty, series can just enable polling on > no-payload requests. Reducing nvme handlers - for another day. Well something needs to be done about multipath since it's broken today: if the path changes between submission and poll, we'll consult the wrong queue for polling enabled. This could cause a missed polling opprotunity, polling a pointer that isn't a bio, or poll an irq enabled cq. All are bad.