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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,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 664CEC433E2 for ; Mon, 31 Aug 2020 18:03:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2F65F20E65 for ; Mon, 31 Aug 2020 18:03:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598897030; bh=tZR2A3lVSdYKcsNK/jg5ppYK+cxjeUefRU6Fal4T1+Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=t6bax8ZJX1DizxECUfUq+K1xAIEnHGJOKbIP1nza8Cy5eYCcXMdA50DbVUiKkWiMH mr2vWqp0XPFjXgKBd/S53S/sOXE8TruATm1IqCyXamn5PFoLdbs/HeYbGm6DFzdePQ SE/2Dtuj+1uawPbr5fdxU5luLpqn/HYkaKkrrPOY= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729309AbgHaSDr (ORCPT ); Mon, 31 Aug 2020 14:03:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:35776 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728388AbgHaSBV (ORCPT ); Mon, 31 Aug 2020 14:01:21 -0400 Received: from paulmck-ThinkPad-P72.home (unknown [50.45.173.55]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id E6E68214DB; Mon, 31 Aug 2020 18:01:20 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1598896881; bh=tZR2A3lVSdYKcsNK/jg5ppYK+cxjeUefRU6Fal4T1+Y=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=HddxuTBEu513gHOumDghphNKW3tHVto/W2NN4yOfvbbhvp60/09bXm6G5p8dX01nl kORMg08osLf65rHnsZzcEhKcWuW8IVl7x02ohfJeHLrPwNVF12s+7rVvXu5PVrO0Cc r1xTt9wRAjUByjjpbPZAzNtLXDggLJ6aI6c+tsEY= 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, dipankar@in.ibm.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 06/24] rcu/trace: Use gp_seq_req in acceleration's rcu_grace_period tracepoint Date: Mon, 31 Aug 2020 11:00:58 -0700 Message-Id: <20200831180116.32690-6-paulmck@kernel.org> X-Mailer: git-send-email 2.9.5 In-Reply-To: <20200831180050.GA32590@paulmck-ThinkPad-P72> References: <20200831180050.GA32590@paulmck-ThinkPad-P72> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Joel Fernandes (Google)" During acceleration of CB, the rsp's gp_seq is rcu_seq_snap'd. This is the value used for acceleration - it is the value of gp_seq at which it is safe the execute all callbacks in the callback list. The rdp's gp_seq is not very useful for this scenario. Make rcu_grace_period report the gp_seq_req instead as it allows one to reason about how the acceleration works. Signed-off-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- kernel/rcu/tree.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index eb36779..8969120 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1483,9 +1483,10 @@ static bool rcu_accelerate_cbs(struct rcu_node *rnp, struct rcu_data *rdp) /* Trace depending on how much we were able to accelerate. */ if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL)) - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccWaitCB")); + trace_rcu_grace_period(rcu_state.name, gp_seq_req, TPS("AccWaitCB")); else - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccReadyCB")); + trace_rcu_grace_period(rcu_state.name, gp_seq_req, TPS("AccReadyCB")); + return ret; } -- 2.9.5