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 E9762CCA47C for ; Mon, 20 Jun 2022 16:19:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242303AbiFTQTV (ORCPT ); Mon, 20 Jun 2022 12:19:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241345AbiFTQTU (ORCPT ); Mon, 20 Jun 2022 12:19:20 -0400 Received: from mx0a-00082601.pphosted.com (mx0a-00082601.pphosted.com [67.231.145.42]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8EA86192BA for ; Mon, 20 Jun 2022 09:19:18 -0700 (PDT) Received: from pps.filterd (m0109333.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 25KFINdq010802 for ; Mon, 20 Jun 2022 09:19:18 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=5INWRad9XhLdGso3ul6etZ2pEm2o7UAnJaQDFkzYueo=; b=HqmLbMwxYHLgKU5xpX+UiLh6FlrFkTgWK4BpV6ddJ7DBxA5gDZC4zGMcTLc8RQ1O6LD6 5Isaj0Du3kmDotq2M7703SwpkkmCQB7Fp2Q8LQtT1bBSUaOYpGok4Pc7r6oT4G0x3Fjt R01oBu+WGnHwQrWGoMg+RpnHBJFCApcExCM= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com (PPS) with ESMTPS id 3gsarpa2cd-2 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Mon, 20 Jun 2022 09:19:18 -0700 Received: from twshared25478.08.ash9.facebook.com (2620:10d:c085:208::11) by mail.thefacebook.com (2620:10d:c085:11d::6) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2375.28; Mon, 20 Jun 2022 09:19:17 -0700 Received: by devbig038.lla2.facebook.com (Postfix, from userid 572232) id 99B441EB9442; Mon, 20 Jun 2022 09:19:05 -0700 (PDT) From: Dylan Yudaken To: , , CC: , Dylan Yudaken Subject: [PATCH RFC for-next 5/8] io_uring: batch task_work Date: Mon, 20 Jun 2022 09:18:58 -0700 Message-ID: <20220620161901.1181971-6-dylany@fb.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20220620161901.1181971-1-dylany@fb.com> References: <20220620161901.1181971-1-dylany@fb.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-FB-Internal: Safe Content-Type: text/plain X-Proofpoint-GUID: cbHq1S7aYCkGCPTueWB_5_hnZduVeVPH X-Proofpoint-ORIG-GUID: cbHq1S7aYCkGCPTueWB_5_hnZduVeVPH X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.64.514 definitions=2022-06-20_05,2022-06-17_01,2022-02-23_01 Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Batching task work up is an important performance optimisation, as task_work_add is expensive. In order to keep the semantics replace the task_list with a fake node while processing the old list, and then do a cmpxchg at the end to see if there is more work. Signed-off-by: Dylan Yudaken --- io_uring/io_uring.c | 24 ++++++++++++++++-------- 1 file changed, 16 insertions(+), 8 deletions(-) diff --git a/io_uring/io_uring.c b/io_uring/io_uring.c index eb29e3f7da5c..0b4d3eb06d16 100644 --- a/io_uring/io_uring.c +++ b/io_uring/io_uring.c @@ -988,9 +988,10 @@ static void ctx_flush_and_put(struct io_ring_ctx *ct= x, bool *locked) =20 =20 static void handle_tw_list(struct llist_node *node, - struct io_ring_ctx **ctx, bool *locked) + struct io_ring_ctx **ctx, bool *locked, + struct llist_node *fake) { - do { + while (node && node !=3D fake) { struct llist_node *next =3D node->next; struct io_kiocb *req =3D container_of(node, struct io_kiocb, io_task_work.node); @@ -1006,7 +1007,10 @@ static void handle_tw_list(struct llist_node *node= , } req->io_task_work.func(req, locked); node =3D next; - } while (node); + count++; + } + + return count; } =20 /** @@ -1045,11 +1049,15 @@ void tctx_task_work(struct callback_head *cb) struct io_ring_ctx *ctx =3D NULL; struct io_uring_task *tctx =3D container_of(cb, struct io_uring_task, task_work); - struct llist_node *node =3D llist_del_all(&tctx->task_list); - - if (node) { - handle_tw_list(node, &ctx, &uring_locked); - cond_resched(); + struct llist_node fake =3D {}; + struct llist_node *node =3D io_llist_xchg(&tctx->task_list, &fake); + + handle_tw_list(node, &ctx, &uring_locked, &fake); + node =3D io_llist_cmpxchg(&tctx->task_list, &fake, NULL); + while (node !=3D &fake) { + node =3D io_llist_xchg(&tctx->task_list, &fake); + handle_tw_list(node, &ctx, &uring_locked, &fake); + node =3D io_llist_cmpxchg(&tctx->task_list, &fake, NULL); } =20 ctx_flush_and_put(ctx, &uring_locked); --=20 2.30.2