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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham 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 C8864C55185 for ; Wed, 22 Apr 2020 16:45:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A34842098B for ; Wed, 22 Apr 2020 16:45:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726534AbgDVQpk (ORCPT ); Wed, 22 Apr 2020 12:45:40 -0400 Received: from foss.arm.com ([217.140.110.172]:52630 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726006AbgDVQpk (ORCPT ); Wed, 22 Apr 2020 12:45:40 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1813B1FB; Wed, 22 Apr 2020 09:45:40 -0700 (PDT) Received: from [192.168.0.7] (unknown [172.31.20.19]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 146903F6CF; Wed, 22 Apr 2020 09:45:37 -0700 (PDT) Subject: Re: [PATCH 04/23] sched,acpi_pad: Convert to sched_set_fifo*() To: Peter Zijlstra , mingo@kernel.org, linux-kernel@vger.kernel.org Cc: tglx@linutronix.de, rostedt@goodmis.org, qais.yousef@arm.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, bsegall@google.com, mgorman@suse.de, rafael.j.wysocki@intel.com References: <20200422112719.826676174@infradead.org> <20200422112831.455977635@infradead.org> From: Dietmar Eggemann Message-ID: Date: Wed, 22 Apr 2020 18:45:36 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 MIME-Version: 1.0 In-Reply-To: <20200422112831.455977635@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 22/04/2020 13:27, Peter Zijlstra wrote: > Because SCHED_FIFO is a broken scheduler model (see previous patches) > take away the priority field, the kernel can't possibly make an > informed decision. > > In this case, use fifo_low, because it only cares about being above > SCHED_NORMAL. Effectively no change in behaviour. > > XXX: this driver is still complete crap; why isn't it using proper > idle injection or at the very least play_idle() ? > > Cc: rafael.j.wysocki@intel.com > Signed-off-by: Peter Zijlstra (Intel) > Reviewed-by: Ingo Molnar > --- > drivers/acpi/acpi_pad.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > --- a/drivers/acpi/acpi_pad.c > +++ b/drivers/acpi/acpi_pad.c > @@ -136,12 +136,11 @@ static unsigned int idle_pct = 5; /* per > static unsigned int round_robin_time = 1; /* second */ > static int power_saving_thread(void *data) > { > - struct sched_param param = {.sched_priority = 1}; > int do_sleep; > unsigned int tsk_index = (unsigned long)data; > u64 last_jiffies = 0; > > - sched_setscheduler(current, SCHED_RR, ¶m); I was wondering what happened to the SCHED_RR cases but as I can see now they are handled here and in the next patch. > + sched_set_fifo_low(current); > > while (!kthread_should_stop()) { > unsigned long expire_time; > >