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 AD8A4EB64DC for ; Fri, 21 Jul 2023 15:51:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232369AbjGUPvj (ORCPT ); Fri, 21 Jul 2023 11:51:39 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51096 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232342AbjGUPvP (ORCPT ); Fri, 21 Jul 2023 11:51:15 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 462F73AB2; Fri, 21 Jul 2023 08:50:49 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 4C05C61D24; Fri, 21 Jul 2023 15:50:35 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AD920C433CA; Fri, 21 Jul 2023 15:50:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1689954634; bh=CkuJeZngoopUBRXmmuGxK5Cdakxf8boSWuNyZaoBpSQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=EM5pMm3fh5CJjXqdvOfpbpclbvkCEZDj1vOo++JTf/LTechKQo3NbfWVRpLuiXOsX egNr/Ja3b3GrUkNXwzaUqTHn87k+8a/57jbcTyS0rKyTvIkMZMyT9LvUhtBiYqIOh0 A48uymLInN2xk/Ipbxt8fNFprsvEhIRv3WhE4omomIlL3YIATb6QRypKO6U0KpmhlY 1hJD/9Imzy7suuKsKx2rOkUFMcJNfCVr+LYR2dpRkiBIPjDwzTnA94Dnsb0gIcLbSw RygBmtMwh3JagW/huBDfsqVTnXPJXM+IJr8GkAbPaTZ/WXjCme0Wi4p+t5Xmz5mPI3 wUtwqZIfyVPIA== Date: Fri, 21 Jul 2023 08:50:34 -0700 From: "Darrick J. Wong" To: Jens Axboe Cc: io-uring@vger.kernel.org, linux-xfs@vger.kernel.org, hch@lst.de, andres@anarazel.de, david@fromorbit.com Subject: Re: [PATCH 7/8] io_uring/rw: add write support for IOCB_DIO_DEFER Message-ID: <20230721155034.GP11352@frogsfrogsfrogs> References: <20230720181310.71589-1-axboe@kernel.dk> <20230720181310.71589-8-axboe@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230720181310.71589-8-axboe@kernel.dk> Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Thu, Jul 20, 2023 at 12:13:09PM -0600, Jens Axboe wrote: > If the filesystem dio handler understands IOCB_DIO_DEFER, we'll get > a kiocb->ki_complete() callback with kiocb->dio_complete set. In that > case, rather than complete the IO directly through task_work, queue > up an intermediate task_work handler that first processes this > callback and then immediately completes the request. > > For XFS, this avoids a punt through a workqueue, which is a lot less > efficient and adds latency to lower queue depth (or sync) O_DIRECT > writes. > > Only do this for non-polled IO, as polled IO doesn't need this kind > of deferral as it always completes within the task itself. This then > avoids a check for deferral in the polled IO completion handler. > > Signed-off-by: Jens Axboe Seems pretty obvious to me, though I'm famous for not being an experienced io_uring user yet... Reviewed-by: Darrick J. Wong --D > --- > io_uring/rw.c | 27 ++++++++++++++++++++++++--- > 1 file changed, 24 insertions(+), 3 deletions(-) > > diff --git a/io_uring/rw.c b/io_uring/rw.c > index 1bce2208b65c..f4f700383b4e 100644 > --- a/io_uring/rw.c > +++ b/io_uring/rw.c > @@ -285,6 +285,14 @@ static inline int io_fixup_rw_res(struct io_kiocb *req, long res) > > void io_req_rw_complete(struct io_kiocb *req, struct io_tw_state *ts) > { > + struct io_rw *rw = io_kiocb_to_cmd(req, struct io_rw); > + > + if (rw->kiocb.dio_complete) { > + long res = rw->kiocb.dio_complete(rw->kiocb.private); > + > + io_req_set_res(req, io_fixup_rw_res(req, res), 0); > + } > + > io_req_io_end(req); > > if (req->flags & (REQ_F_BUFFER_SELECTED|REQ_F_BUFFER_RING)) { > @@ -300,9 +308,11 @@ static void io_complete_rw(struct kiocb *kiocb, long res) > struct io_rw *rw = container_of(kiocb, struct io_rw, kiocb); > struct io_kiocb *req = cmd_to_io_kiocb(rw); > > - if (__io_complete_rw_common(req, res)) > - return; > - io_req_set_res(req, io_fixup_rw_res(req, res), 0); > + if (!rw->kiocb.dio_complete) { > + if (__io_complete_rw_common(req, res)) > + return; > + io_req_set_res(req, io_fixup_rw_res(req, res), 0); > + } > req->io_task_work.func = io_req_rw_complete; > __io_req_task_work_add(req, IOU_F_TWQ_LAZY_WAKE); > } > @@ -916,6 +926,17 @@ int io_write(struct io_kiocb *req, unsigned int issue_flags) > } > kiocb->ki_flags |= IOCB_WRITE; > > + /* > + * For non-polled IO, set IOCB_DIO_DEFER, stating that our handler > + * groks deferring the completion to task context. This isn't > + * necessary and useful for polled IO as that can always complete > + * directly. > + */ > + if (!(kiocb->ki_flags & IOCB_HIPRI)) { > + kiocb->ki_flags |= IOCB_DIO_DEFER; > + kiocb->dio_complete = NULL; > + } > + > if (likely(req->file->f_op->write_iter)) > ret2 = call_write_iter(req->file, kiocb, &s->iter); > else if (req->file->f_op->write) > -- > 2.40.1