From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755442Ab0AMK01 (ORCPT ); Wed, 13 Jan 2010 05:26:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755333Ab0AMK0Z (ORCPT ); Wed, 13 Jan 2010 05:26:25 -0500 Received: from hera.kernel.org ([140.211.167.34]:38044 "EHLO hera.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753728Ab0AMK0X (ORCPT ); Wed, 13 Jan 2010 05:26:23 -0500 Date: Wed, 13 Jan 2010 10:25:53 GMT From: "tip-bot for Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, paulmck@linux.vnet.ibm.com, hpa@zytor.com, mingo@redhat.com, tglx@linutronix.de, mingo@elte.hu Reply-To: mingo@redhat.com, hpa@zytor.com, paulmck@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@elte.hu In-Reply-To: <12626465502985-git-send-email-> References: <12626465502985-git-send-email-> To: linux-tip-commits@vger.kernel.org Subject: [tip:core/rcu] rcu: Eliminate local variable lastcomp from force_quiescent_state() Message-ID: Git-Commit-ID: 39c0bbfc07c6e28db7346d0e11106f2d045d3035 X-Mailer: tip-git-log-daemon MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.3 (hera.kernel.org [127.0.0.1]); Wed, 13 Jan 2010 10:25:54 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: 39c0bbfc07c6e28db7346d0e11106f2d045d3035 Gitweb: http://git.kernel.org/tip/39c0bbfc07c6e28db7346d0e11106f2d045d3035 Author: Paul E. McKenney AuthorDate: Mon, 4 Jan 2010 15:09:04 -0800 Committer: Ingo Molnar CommitDate: Wed, 13 Jan 2010 09:06:03 +0100 rcu: Eliminate local variable lastcomp from force_quiescent_state() Because rsp->fqs_active is set to 1 across force_quiescent_state()'s switch statement, rcu_start_gp() will refrain from starting a new grace period during this time. Therefore, rsp->gpnum is constant, and can be propagated to all uses of lastcomp, eliminating this local variable. Signed-off-by: Paul E. McKenney Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <12626465502985-git-send-email-> Signed-off-by: Ingo Molnar --- kernel/rcutree.c | 10 +++------- kernel/rcutree.h | 2 -- 2 files changed, 3 insertions(+), 9 deletions(-) diff --git a/kernel/rcutree.c b/kernel/rcutree.c index 1d8cfb1..62b6433 100644 --- a/kernel/rcutree.c +++ b/kernel/rcutree.c @@ -1191,7 +1191,6 @@ static int rcu_process_dyntick(struct rcu_state *rsp, long lastcomp, static void force_quiescent_state(struct rcu_state *rsp, int relaxed) { unsigned long flags; - long lastcomp; struct rcu_node *rnp = rcu_get_root(rsp); u8 forcenow; u8 gpdone; @@ -1207,7 +1206,6 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) goto unlock_fqs_ret; /* no emergency and done recently. */ rsp->n_force_qs++; spin_lock(&rnp->lock); /* irqs already disabled */ - lastcomp = rsp->gpnum - 1; rsp->jiffies_force_qs = jiffies + RCU_JIFFIES_TILL_FORCE_QS; if(!rcu_gp_in_progress(rsp)) { rsp->n_force_qs_ngp++; @@ -1228,7 +1226,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) break; /* So gcc recognizes the dead code. */ /* Record dyntick-idle state. */ - gpdone = rcu_process_dyntick(rsp, lastcomp, + gpdone = rcu_process_dyntick(rsp, rsp->gpnum - 1, dyntick_save_progress_counter); spin_lock(&rnp->lock); /* irqs already disabled */ if (gpdone) @@ -1239,11 +1237,9 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) /* Update state, record completion counter. */ forcenow = 0; - if (lastcomp + 1 == rsp->gpnum && - lastcomp == rsp->completed) { + if (rsp->gpnum - 1 == rsp->completed) { forcenow = rsp->signaled == RCU_SAVE_COMPLETED; rsp->signaled = RCU_FORCE_QS; - rsp->completed_fqs = lastcomp; } if (!forcenow) break; @@ -1253,7 +1249,7 @@ static void force_quiescent_state(struct rcu_state *rsp, int relaxed) /* Check dyntick-idle state, send IPI to laggarts. */ spin_unlock(&rnp->lock); /* irqs remain disabled */ - gpdone = rcu_process_dyntick(rsp, rsp->completed_fqs, + gpdone = rcu_process_dyntick(rsp, rsp->gpnum - 1, rcu_implicit_dynticks_qs); /* Leave state in case more forcing is required. */ diff --git a/kernel/rcutree.h b/kernel/rcutree.h index dc386a7..5348561 100644 --- a/kernel/rcutree.h +++ b/kernel/rcutree.h @@ -296,8 +296,6 @@ struct rcu_state { long orphan_qlen; /* Number of orphaned cbs. */ spinlock_t fqslock; /* Only one task forcing */ /* quiescent states. */ - long completed_fqs; /* Value of completed @ snap. */ - /* Protected by fqslock. */ unsigned long jiffies_force_qs; /* Time at which to invoke */ /* force_quiescent_state(). */ unsigned long n_force_qs; /* Number of calls to */