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 X-Spam-Level: X-Spam-Status: No, score=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id EA0B4C433E0 for ; Wed, 6 Jan 2021 17:19:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C36CF23106 for ; Wed, 6 Jan 2021 17:19:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728002AbhAFRTK (ORCPT ); Wed, 6 Jan 2021 12:19:10 -0500 Received: from mail.kernel.org ([198.145.29.99]:60794 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726723AbhAFRSe (ORCPT ); Wed, 6 Jan 2021 12:18:34 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 7D9552313C; Wed, 6 Jan 2021 17:17:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1609953433; bh=OGmZDzqwgbWi9Rg4zkjdMdAemN0aue1H41mwDuz02LE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=NZkgg9I3zmhdDKy51Zxoz8OGFmq00aMGBUSquwjmP3QF2MaQQ/D5TNoQZvJDEyUQo akAorX2f9/2HsdFwCl5dMAC3ZiKAlYrDYXgi/anNUpqJngF+pBJR2JL6Q6cFh24bRB R6Kwz+pCfSzTpd/NKwVton8MMAo0rksp0zF3wOygRPHLl86498A6y5XkY66Z98janC vqS5qdjVWlJH9sQNjqT7Vi8pg7aSUzrU/mJ0Lag8e9a5ULkU29TpTy06ghLefppvHQ FAc9M2RbjVpjjgKku9cupyw32qVic+P1XRc65pXJYxjQYfvWljeh/CJYmAfn0A6TSL mBtC/o69c+dpw== From: paulmck@kernel.org To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@fb.com, mingo@kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 08/17] rcutorture: Use torture_hrtimeout_jiffies() to avoid busy-waits Date: Wed, 6 Jan 2021 09:17:01 -0800 Message-Id: <20210106171710.22239-8-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20210106171532.GA20769@paulmck-ThinkPad-P72> References: <20210106171532.GA20769@paulmck-ThinkPad-P72> Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: "Paul E. McKenney" Because rcu_torture_writer() and rcu_torture_fakewriter() predate hrtimers, they do timer-wheel-decoupled timed waits by using the timer-wheel-based schedule_timeout_interruptible() functions in conjunction with a random udelay()-based wait. This latter unnecessarily burns CPU time, so this commit instead uses torture_hrtimeout_jiffies() to decouple from the timer wheels without busy-waiting. Signed-off-by: Paul E. McKenney --- kernel/rcu/rcutorture.c | 26 +++++++------------------- 1 file changed, 7 insertions(+), 19 deletions(-) diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c index 1b70aa4..7b61086 100644 --- a/kernel/rcu/rcutorture.c +++ b/kernel/rcu/rcutorture.c @@ -1194,10 +1194,7 @@ rcu_torture_writer(void *arg) case RTWS_COND_GET: rcu_torture_writer_state = RTWS_COND_GET; gp_snap = cur_ops->get_gp_state(); - i = torture_random(&rand) % 16; - if (i != 0) - schedule_timeout_interruptible(i); - udelay(torture_random(&rand) % 1000); + torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand); rcu_torture_writer_state = RTWS_COND_SYNC; cur_ops->cond_sync(gp_snap); rcu_torture_pipe_update(old_rp); @@ -1206,12 +1203,9 @@ rcu_torture_writer(void *arg) rcu_torture_writer_state = RTWS_POLL_GET; gp_snap = cur_ops->start_gp_poll(); rcu_torture_writer_state = RTWS_POLL_WAIT; - while (!cur_ops->poll_gp_state(gp_snap)) { - i = torture_random(&rand) % 16; - if (i != 0) - schedule_timeout_interruptible(i); - udelay(torture_random(&rand) % 1000); - } + while (!cur_ops->poll_gp_state(gp_snap)) + torture_hrtimeout_jiffies(torture_random(&rand) % 16, + &rand); rcu_torture_pipe_update(old_rp); break; case RTWS_SYNC: @@ -1290,7 +1284,6 @@ static int rcu_torture_fakewriter(void *arg) { unsigned long gp_snap; - int i; DEFINE_TORTURE_RANDOM(rand); VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started"); @@ -1311,19 +1304,14 @@ rcu_torture_fakewriter(void *arg) break; case RTWS_COND_GET: gp_snap = cur_ops->get_gp_state(); - i = torture_random(&rand) % 16; - if (i != 0) - schedule_timeout_interruptible(i); - udelay(torture_random(&rand) % 1000); + torture_hrtimeout_jiffies(torture_random(&rand) % 16, &rand); cur_ops->cond_sync(gp_snap); break; case RTWS_POLL_GET: gp_snap = cur_ops->start_gp_poll(); while (!cur_ops->poll_gp_state(gp_snap)) { - i = torture_random(&rand) % 16; - if (i != 0) - schedule_timeout_interruptible(i); - udelay(torture_random(&rand) % 1000); + torture_hrtimeout_jiffies(torture_random(&rand) % 16, + &rand); } break; case RTWS_SYNC: -- 2.9.5