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=-4.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 7991FC56202 for ; Wed, 28 Oct 2020 22:18:58 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 23F8A206E3 for ; Wed, 28 Oct 2020 22:18:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603923538; bh=X+30g5YKs+8oMJAS08Jtf2Iv1iwIT2fJ6zl6TGlh4c0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=IrOXi2JuocUQw0QwCdT3hUXR424vVXR+ly9gOtNvT0XhCFsY3es4sf4/mo20BN01m EF9vtDqm2DrEqMpbz8BnpYoOE3CGJLXddl3trG4/4WEzxA92PAP+0sdDV+lngFfAM/ zo7Dbrvtr8Hse6g9+GPjCWj1pN/uiumGyJz8ebq8= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732039AbgJ1WS2 (ORCPT ); Wed, 28 Oct 2020 18:18:28 -0400 Received: from mail.kernel.org ([198.145.29.99]:60510 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731770AbgJ1WRo (ORCPT ); Wed, 28 Oct 2020 18:17:44 -0400 Received: from localhost (i15-lef02-th2-89-83-213-3.ft.lns.abo.bbox.fr [89.83.213.3]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EB5CE24671; Wed, 28 Oct 2020 13:40:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603892449; bh=X+30g5YKs+8oMJAS08Jtf2Iv1iwIT2fJ6zl6TGlh4c0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=GiE/4m+2qKi44EdTLOJq9woqLAqa9zK6WQhFMIR7IT3pSPyDtsPF5L0WbvRHzL/Qz R9ajM/JSCzCNsHy6sFJwpvvIVi+xmdQoOjhs6tb+mucoTfkn4LiYmtrKlto0ASQCg7 fylS9KmjCR69M8eBTLc/I5mv/4Q8jGpb2qjhxq1o= Date: Wed, 28 Oct 2020 14:40:46 +0100 From: Frederic Weisbecker To: Peter Zijlstra Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, will@kernel.org, paulmck@kernel.org, hch@lst.de, axboe@kernel.dk, chris@chris-wilson.co.uk, davem@davemloft.net, kuba@kernel.org, fweisbec@gmail.com, oleg@redhat.com, vincent.guittot@linaro.org Subject: Re: [PATCH v3 5/6] irq_work: Provide irq_work_queue_remote() Message-ID: <20201028134046.GE229044@lothringen> References: <20201028110707.971887448@infradead.org> <20201028111221.526249871@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201028111221.526249871@infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 28, 2020 at 12:07:12PM +0100, Peter Zijlstra wrote: > While the traditional irq_work relies on the ability to self-IPI, it > makes sense to provide an unconditional irq_work_queue_remote() > interface. We may need a reason as well here. > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -1308,13 +1308,14 @@ static int rcu_implicit_dynticks_qs(stru > resched_cpu(rdp->cpu); > WRITE_ONCE(rdp->last_fqs_resched, jiffies); > } > - if (IS_ENABLED(CONFIG_IRQ_WORK) && > - !rdp->rcu_iw_pending && rdp->rcu_iw_gp_seq != rnp->gp_seq && > +#ifdef CONFIG_IRQ_WORK > + if (!rdp->rcu_iw_pending && rdp->rcu_iw_gp_seq != rnp->gp_seq && If it's unconditional on SMP, I expect it to be unconditional on rcutree. Also this chunk seems unrelated to this patch. > (rnp->ffmask & rdp->grpmask)) { > rdp->rcu_iw_pending = true; > rdp->rcu_iw_gp_seq = rnp->gp_seq; > irq_work_queue_on(&rdp->rcu_iw, rdp->cpu); > } > +#endif > } > > return 0; > >