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 AA84AC43334 for ; Tue, 21 Jun 2022 10:02:47 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237689AbiFUKCq (ORCPT ); Tue, 21 Jun 2022 06:02:46 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42476 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231847AbiFUKCm (ORCPT ); Tue, 21 Jun 2022 06:02:42 -0400 Received: from alexa-out-sd-01.qualcomm.com (alexa-out-sd-01.qualcomm.com [199.106.114.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DF3CD27FE6; Tue, 21 Jun 2022 03:02:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1655805761; x=1687341761; h=message-id:date:mime-version:subject:to:cc:references: from:in-reply-to:content-transfer-encoding; bh=QVzdBNyMcQCp/AEcPlHdcIajijCDUBwKc+Y/v0orBkM=; b=eqnyOnIjL/YKQUBORWQy/F+HIltdSWTHTpqzj57zBW+s6AG7Mv5mHdQJ N/VQrsW+WcAOtjmldSSDLC+IIfQCBgABxsEaGcbdSEe+IFwOXLPZkQXgx V5XjpUfqbpnvzB+sAJ/4SUpKj8PuuaaiNm6iQR61TRsOZ/r0+zUOzjbX0 w=; Received: from unknown (HELO ironmsg-SD-alpha.qualcomm.com) ([10.53.140.30]) by alexa-out-sd-01.qualcomm.com with ESMTP; 21 Jun 2022 03:02:41 -0700 X-QCInternal: smtphost Received: from nasanex01b.na.qualcomm.com ([10.46.141.250]) by ironmsg-SD-alpha.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 21 Jun 2022 03:02:41 -0700 Received: from [10.50.44.13] (10.80.80.8) by nasanex01b.na.qualcomm.com (10.46.141.250) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Tue, 21 Jun 2022 03:02:39 -0700 Message-ID: Date: Tue, 21 Jun 2022 15:32:36 +0530 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.9.1 Subject: Re: [PATCH rcu 09/12] rcu/kvfree: Remove useless monitor_todo flag Content-Language: en-US To: "Paul E. McKenney" , CC: , , , "Joel Fernandes (Google)" , Uladzislau Rezki References: <20220620222022.GA3839466@paulmck-ThinkPad-P17-Gen-1> <20220620222032.3839547-9-paulmck@kernel.org> From: Neeraj Upadhyay In-Reply-To: <20220620222032.3839547-9-paulmck@kernel.org> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01a.na.qualcomm.com (10.52.223.231) To nasanex01b.na.qualcomm.com (10.46.141.250) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/21/2022 3:50 AM, Paul E. McKenney wrote: > From: "Joel Fernandes (Google)" > > monitor_todo is not needed as the work struct already tracks > if work is pending. Just use that to know if work is pending > using schedule_delayed_work() helper. > > Signed-off-by: Joel Fernandes (Google) > Signed-off-by: Uladzislau Rezki (Sony) > Signed-off-by: Paul E. McKenney > --- Reviewed-by: Neeraj Upadhyay Thanks Neeraj > kernel/rcu/tree.c | 33 ++++++++++++++++----------------- > 1 file changed, 16 insertions(+), 17 deletions(-) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 5445b19b48408..7919d7b48fa6a 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -3216,7 +3216,6 @@ struct kfree_rcu_cpu_work { > * @krw_arr: Array of batches of kfree_rcu() objects waiting for a grace period > * @lock: Synchronize access to this structure > * @monitor_work: Promote @head to @head_free after KFREE_DRAIN_JIFFIES > - * @monitor_todo: Tracks whether a @monitor_work delayed work is pending > * @initialized: The @rcu_work fields have been initialized > * @count: Number of objects for which GP not started > * @bkvcache: > @@ -3241,7 +3240,6 @@ struct kfree_rcu_cpu { > struct kfree_rcu_cpu_work krw_arr[KFREE_N_BATCHES]; > raw_spinlock_t lock; > struct delayed_work monitor_work; > - bool monitor_todo; > bool initialized; > int count; > > @@ -3421,6 +3419,18 @@ static void kfree_rcu_work(struct work_struct *work) > } > } > > +static bool > +need_offload_krc(struct kfree_rcu_cpu *krcp) > +{ > + int i; > + > + for (i = 0; i < FREE_N_CHANNELS; i++) > + if (krcp->bkvhead[i]) > + return true; > + > + return !!krcp->head; > +} > + > /* > * This function is invoked after the KFREE_DRAIN_JIFFIES timeout. > */ > @@ -3477,9 +3487,7 @@ static void kfree_rcu_monitor(struct work_struct *work) > // of the channels that is still busy we should rearm the > // work to repeat an attempt. Because previous batches are > // still in progress. > - if (!krcp->bkvhead[0] && !krcp->bkvhead[1] && !krcp->head) > - krcp->monitor_todo = false; > - else > + if (need_offload_krc(krcp)) > schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); > > raw_spin_unlock_irqrestore(&krcp->lock, flags); > @@ -3667,11 +3675,8 @@ void kvfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > WRITE_ONCE(krcp->count, krcp->count + 1); > > // Set timer to drain after KFREE_DRAIN_JIFFIES. > - if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING && > - !krcp->monitor_todo) { > - krcp->monitor_todo = true; > + if (rcu_scheduler_active == RCU_SCHEDULER_RUNNING) > schedule_delayed_work(&krcp->monitor_work, KFREE_DRAIN_JIFFIES); > - } > > unlock_return: > krc_this_cpu_unlock(krcp, flags); > @@ -3746,14 +3751,8 @@ void __init kfree_rcu_scheduler_running(void) > struct kfree_rcu_cpu *krcp = per_cpu_ptr(&krc, cpu); > > raw_spin_lock_irqsave(&krcp->lock, flags); > - if ((!krcp->bkvhead[0] && !krcp->bkvhead[1] && !krcp->head) || > - krcp->monitor_todo) { > - raw_spin_unlock_irqrestore(&krcp->lock, flags); > - continue; > - } > - krcp->monitor_todo = true; > - schedule_delayed_work_on(cpu, &krcp->monitor_work, > - KFREE_DRAIN_JIFFIES); > + if (need_offload_krc(krcp)) > + schedule_delayed_work_on(cpu, &krcp->monitor_work, KFREE_DRAIN_JIFFIES); > raw_spin_unlock_irqrestore(&krcp->lock, flags); > } > }