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 506A6C76188 for ; Mon, 3 Apr 2023 14:21:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233136AbjDCOVP (ORCPT ); Mon, 3 Apr 2023 10:21:15 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41794 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233142AbjDCOVF (ORCPT ); Mon, 3 Apr 2023 10:21:05 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BF029312AC for ; Mon, 3 Apr 2023 07:20:46 -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 05FF361A2D for ; Mon, 3 Apr 2023 14:20:13 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 179EEC4339C; Mon, 3 Apr 2023 14:20:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680531612; bh=9d7Anayty8RhvVuNsOs31H6y62ZkLu4OYTN4Le6kfuk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=GbbsFGRI1K92c/CA+ADqwx0Qz/86XvClUUND5G1kanggcsc8LKsYm+EqREEcK+zzI 6VpRxYgXbqVauiKmSoAL7OBnJNKBQfRwr5qZiZ9MsWjbyI0LSMgs6XmWSrFemPnbQw bA+5EAav5bwofTbAZMi6JthhgtG3+P11pSR5by6I= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Nathan Huckleberry , Eric Biggers Subject: [PATCH 5.4 045/104] fsverity: Remove WQ_UNBOUND from fsverity read workqueue Date: Mon, 3 Apr 2023 16:08:37 +0200 Message-Id: <20230403140406.159854304@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230403140403.549815164@linuxfoundation.org> References: <20230403140403.549815164@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Nathan Huckleberry commit f959325e6ac3f499450088b8d9c626d1177be160 upstream. WQ_UNBOUND causes significant scheduler latency on ARM64/Android. This is problematic for latency sensitive workloads, like I/O post-processing. Removing WQ_UNBOUND gives a 96% reduction in fsverity workqueue related scheduler latency and improves app cold startup times by ~30ms. WQ_UNBOUND was also removed from the dm-verity workqueue for the same reason [1]. This code was tested by running Android app startup benchmarks and measuring how long the fsverity workqueue spent in the runnable state. Before Total workqueue scheduler latency: 553800us After Total workqueue scheduler latency: 18962us [1]: https://lore.kernel.org/all/20230202012348.885402-1-nhuck@google.com/ Signed-off-by: Nathan Huckleberry Fixes: 8a1d0f9cacc9 ("fs-verity: add data verification hooks for ->readpages()") Cc: stable@vger.kernel.org Link: https://lore.kernel.org/r/20230310193325.620493-1-nhuck@google.com Signed-off-by: Eric Biggers Signed-off-by: Greg Kroah-Hartman --- fs/verity/verify.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) --- a/fs/verity/verify.c +++ b/fs/verity/verify.c @@ -259,15 +259,15 @@ EXPORT_SYMBOL_GPL(fsverity_enqueue_verif int __init fsverity_init_workqueue(void) { /* - * Use an unbound workqueue to allow bios to be verified in parallel - * even when they happen to complete on the same CPU. This sacrifices - * locality, but it's worthwhile since hashing is CPU-intensive. + * Use a high-priority workqueue to prioritize verification work, which + * blocks reads from completing, over regular application tasks. * - * Also use a high-priority workqueue to prioritize verification work, - * which blocks reads from completing, over regular application tasks. + * For performance reasons, don't use an unbound workqueue. Using an + * unbound workqueue for crypto operations causes excessive scheduler + * latency on ARM64. */ fsverity_read_workqueue = alloc_workqueue("fsverity_read_queue", - WQ_UNBOUND | WQ_HIGHPRI, + WQ_HIGHPRI, num_online_cpus()); if (!fsverity_read_workqueue) return -ENOMEM;