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=-19.0 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,URIBL_BLOCKED,USER_AGENT_GIT autolearn=unavailable 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 85525C43333 for ; Thu, 4 Mar 2021 01:08:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 70F3C64E99 for ; Thu, 4 Mar 2021 01:08:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1356409AbhCDBEh (ORCPT ); Wed, 3 Mar 2021 20:04:37 -0500 Received: from mail.kernel.org ([198.145.29.99]:54734 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1451174AbhCDAak (ORCPT ); Wed, 3 Mar 2021 19:30:40 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9B21164EF4; Thu, 4 Mar 2021 00:29:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614817797; bh=5LqAc5v3vAiyIyBEf5zKjssRCh70Z9FmZPs7b9Jz4JM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=J8IRZk6qPmyZJxPNEGzQIx3PRSLjs+5ORKsZurhoHq/A8yJ+c2ahUggdyMii8ITR2 8rCpfJ2rsKRVcCjTrtWgJVZna1x1gJCm1vhJ+UOf9QRiGeXg+nSNkbYR0kkze/ekCq sLfvHStuSmB2dc/dJWnm1JamwNUSH87v1oDRlxxIWdCflUJYzKftx4r7vMKCzDkkX3 2rB3GsO1ooiD0xS/6vjqxyXfqhwcMnIAo+6ya69h2eVh6pLR9L2Tre487Nm9tVfd30 rhcSF4FZhSb03G/67nk5Dioc/f80ZOCD3OP044uo9hgqr8lOUd6enN/DGMR6ldk74i rWm3sYxGUkSjQ== 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 5/5] torture: Make jitter.sh handle large systems Date: Wed, 3 Mar 2021 16:29:55 -0800 Message-Id: <20210304002955.24132-5-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20210304002919.GA24003@paulmck-ThinkPad-P72> References: <20210304002919.GA24003@paulmck-ThinkPad-P72> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Paul E. McKenney" The current jitter.sh script expects cpumask bits to fit into whatever the awk interpreter uses for an integer, which clearly does not hold for even medium-sized systems these days. This means that on a large system, only the first 32 or 64 CPUs (depending) are subjected to jitter.sh CPU-time perturbations. This commit therefore computes a given CPU's cpumask using text manipulation rather than arithmetic shifts. Reported-by: Sebastian Andrzej Siewior Signed-off-by: Paul E. McKenney --- tools/testing/selftests/rcutorture/bin/jitter.sh | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/tools/testing/selftests/rcutorture/bin/jitter.sh b/tools/testing/selftests/rcutorture/bin/jitter.sh index 188b864..3a856ec 100755 --- a/tools/testing/selftests/rcutorture/bin/jitter.sh +++ b/tools/testing/selftests/rcutorture/bin/jitter.sh @@ -67,10 +67,10 @@ do srand(n + me + systime()); ncpus = split(cpus, ca); curcpu = ca[int(rand() * ncpus + 1)]; - mask = lshift(1, curcpu); - if (mask + 0 <= 0) - mask = 1; - printf("%#x\n", mask); + z = ""; + for (i = 1; 4 * i <= curcpu; i++) + z = z "0"; + print "0x" 2 ^ (curcpu % 4) z; }' < /dev/null` n=$(($n+1)) if ! taskset -p $cpumask $$ > /dev/null 2>&1 -- 2.9.5