From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 90C3615746E for ; Thu, 11 Sep 2025 02:06:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757556401; cv=none; b=mG+SLsAYLEHWEEHMa73TQ764EyEyJ5gGOSScJWQtRS0WchrsvV+9zQfolsVM76BJX/YIruHC4GPSfE0yN5Xn8SoVVWZBdMUg0uxpdri4Nxrs4KxsfukMtq1o8Sc2G/vrK6Km2ORA2yW0BS3gtPRMDb9wNMmJFnApCE52Rd131e8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1757556401; c=relaxed/simple; bh=WtaIn3MR8xwUk9n6PcYwXTpq5iluJhqa5/j6R/szb+w=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=c9lTaG9ZvU1jFKK9qd3pWcfRCltrf+dWXkBPXBKXR/jBDvVca+h37I1CNpxF8xx+9U5lWys4osjF5ZI1ORHzenO02+APykOT7NAIQTY/p4RQuvG9Rn2XTV66loYD0v1G3n9x78AkcUeoHP2ogCVAMJC+tIQFs1kikPa4g+zHHPU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=M1QtyayA; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="M1QtyayA" Received: by smtp.kernel.org (Postfix) with ESMTPSA id F1D1EC4CEEB; Thu, 11 Sep 2025 02:06:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1757556401; bh=WtaIn3MR8xwUk9n6PcYwXTpq5iluJhqa5/j6R/szb+w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=M1QtyayAOkMnHKY1o+Qy7e/waLs5W1mObtqdB7tW5B1a/K0ml5lN6NqQZjMFSCxse uzSwI+ksBRIAM/T5mDpIcq/9amBKyXUDJscLJcXAt4wavF3r88Zx1Uv1DI9jvkFVkv /ZJ0Eb3pGRqYyFFWVQmV1xrWds81zIei4BPHuOA/xcOfCikERNDutqCUWl5xKlypSo /P4xfk3Qk69M5qlp8EzsxsUVKndPShbrfTGMKFAKDCpsu6nwaY0VgW7bzbGRGSBpNS R2wdWv2osBaOUBPnqJGqv85/AB9YJ4onG/+BekWCZBIVkds+t9tmqBrUES7WVwz8Dr s+JC0vKDustsQ== Date: Wed, 10 Sep 2025 22:06:37 -0400 From: Keith Busch To: Caleb Sander Mateos Cc: Keith Busch , io-uring@vger.kernel.org, axboe@kernel.dk Subject: Re: [RFC PATCHv2 1/1] io_uring: add support for IORING_SETUP_SQE_MIXED Message-ID: References: <20250904192716.3064736-1-kbusch@meta.com> <20250904192716.3064736-3-kbusch@meta.com> Precedence: bulk X-Mailing-List: io-uring@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: On Wed, Sep 10, 2025 at 10:44:10AM -0700, Caleb Sander Mateos wrote: > On Thu, Sep 4, 2025 at 12:27 PM Keith Busch wrote: > > diff --git a/include/uapi/linux/io_uring.h b/include/uapi/linux/io_uring.h > > index 04ebff33d0e62..9cef9085f52ee 100644 > > --- a/include/uapi/linux/io_uring.h > > +++ b/include/uapi/linux/io_uring.h > > @@ -146,6 +146,7 @@ enum io_uring_sqe_flags_bit { > > IOSQE_ASYNC_BIT, > > IOSQE_BUFFER_SELECT_BIT, > > IOSQE_CQE_SKIP_SUCCESS_BIT, > > + IOSQE_SQE_128B_BIT, > > Have you given any thought to how we would handle the likely scenario > that we want to define more SQE flags in the future? Are there > existing unused bytes of the SQE where the new flags could go? If not, > we may need to repurpose some existing but rarely used field. And then > we'd likely want to reserve this last flag bit to specify whether the > SQE is using this "extended flags" field. Yeah, I mentioned in the cover letter it may not okay to take this bit for the cause. Using it this way is just a simple way forward for the proof-of-concept to iron out handling mixed SQEs everywhere else. I wouldn't remove the "RFC" prefix until we have agreement on how to flag a big SQE command on a mixed SQ. One option, for example, might take the highest opcode bit since we're a ways off off from needing it for more ops.