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 6ABF1C77B61 for ; Mon, 24 Apr 2023 17:36:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232206AbjDXRgM (ORCPT ); Mon, 24 Apr 2023 13:36:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231921AbjDXRgK (ORCPT ); Mon, 24 Apr 2023 13:36:10 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1DE2D900E; Mon, 24 Apr 2023 10:35:55 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id A56A562770; Mon, 24 Apr 2023 17:35:54 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 14DA6C433D2; Mon, 24 Apr 2023 17:35:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1682357754; bh=aLtMvp4ULEMd8pl1Q8wn1UwIesflr0PbMKXka8Q/Qb0=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=flz29u61LJHfAaR/NpMlAxxSBgcG5GROzPKresGaqDLCRMs+SS6vVJnbQS+rD4DBz BdsrjZNTXOIk97UXe6c6uMpok/gxUhU9kghbm/9HXINqh5HlcZi6Zz7LbtgB6WAJkW na84K40jnXAnAwB4UWAony876EhDMjLj0aamWYkluoZl9aZH6DDA/5o+yVtfVjYErV a04kpt6U9tj60ldPyCJSUVqoiizRn8fX17oUHuJLLgqvjMt7S6GXgE0p58igl3qziy PjsiKDPSBvDzlXT7Pqs4hf+sGwllEPX1gV4z22vOKBPrpL/4tCXuuGIRF3caH0zBre CyiNWjsj0C7vw== Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id AE7F115404E7; Mon, 24 Apr 2023 10:35:53 -0700 (PDT) Date: Mon, 24 Apr 2023 10:35:53 -0700 From: "Paul E. McKenney" To: Uladzislau Rezki Cc: Zqiang , frederic@kernel.org, joel@joelfernandes.org, qiang.zhang1211@gmail.com, rcu@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] rcu/kvfree: Make drain_page_cache() call return directly if cache is disabled Message-ID: <4281adc2-ebb9-4595-9b21-e773bda35f7b@paulmck-laptop> Reply-To: paulmck@kernel.org References: <20230418122702.1378299-1-qiang1.zhang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 20, 2023 at 01:06:27PM +0200, Uladzislau Rezki wrote: > On Tue, Apr 18, 2023 at 08:27:02PM +0800, Zqiang wrote: > > If the rcu_min_cached_objs is set to zero at boot params, the > > krcp->page_cache_work will not be triggered to fill page cache, > > and the put_cached_bnode() also does not fill page cache, this > > also means the krcp->bkvcache is always empty, so not need to > > acquire unnecessary krcp->lock to get page from krcp->bkvcache, > > this commit therefore make drain_page_cache() return directly if > > the rcu_min_cached_objs is zero. > > > > Signed-off-by: Zqiang > > --- > > kernel/rcu/tree.c | 3 +++ > > 1 file changed, 3 insertions(+) > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 93faf9f5c58f..00620a2117de 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -2924,6 +2924,9 @@ drain_page_cache(struct kfree_rcu_cpu *krcp) > > struct llist_node *page_list, *pos, *n; > > int freed = 0; > > > > + if (!rcu_min_cached_objs) > > + return 0; > > + > > raw_spin_lock_irqsave(&krcp->lock, flags); > > page_list = llist_del_all(&krcp->bkvcache); > > WRITE_ONCE(krcp->nr_bkv_objs, 0); > > -- > > 2.32.0 > > > Reviewed-by: Uladzislau Rezki (Sony) Queued for further testing and review, thank you both! Thanx, Paul