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=-5.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, 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 4CC9EC32750 for ; Fri, 2 Aug 2019 08:58:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 22F082173E for ; Fri, 2 Aug 2019 08:58:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="KfNlPhD/" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2404543AbfHBI63 (ORCPT ); Fri, 2 Aug 2019 04:58:29 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:59442 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730713AbfHBI63 (ORCPT ); Fri, 2 Aug 2019 04:58:29 -0400 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Type:MIME-Version :References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=/G68ut9V+Igim0AzrVXEipFOU/9WLiFOX2nUkkTzcHQ=; b=KfNlPhD/w0UbDGnpbQ/REn0g5 6oaHKUks286tOKhZrh0THjEFBcX0GnWm4wlc7dM/dE/tQt/QinHekViEpxBHAU31xJYisJ1ImvD+u IqpEAalcoLdPcKZmnjch3UmCNRFXiYYEIyWVAXxuzpRYq7wGWCpdodB3sl596Oi8B8hbx4wfjUce+ IysR9ne7zYm5MkQSf+qwkFNx6qguUN7IGAqVbbdib3hW3k1mKdN3YbEBD+2ABgfIYhuD4CRQ1BL/p KxK3a5Q2hejzudSbGl5ltFHV8NY5bJcueUNA3dmbjdcRMaevhFG8QlFFzqEH3eDnhnJdVgTqSfRAb F8fcXznWw==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.92 #3 (Red Hat Linux)) id 1htTOK-0005K4-Bu; Fri, 02 Aug 2019 08:58:24 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9C8C32029F4CB; Fri, 2 Aug 2019 10:58:22 +0200 (CEST) Date: Fri, 2 Aug 2019 10:58:22 +0200 From: Peter Zijlstra To: Andy Walls Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, Andy Walls , Mauro Carvalho Chehab , linux-media@vger.kernel.org, Thomas Gleixner Subject: Re: [PATCH 4/5] media/ivtv: Reduce default FIFO priority Message-ID: <20190802085822.GA2386@hirez.programming.kicks-ass.net> References: <20190801111348.530242235@infradead.org> <20190801111541.858088180@infradead.org> <7970f0e30d1eb83e7067225d07b923863bf1ac50.camel@silverblocksystems.net> <20190801123806.GA31398@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190801123806.GA31398@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Aug 01, 2019 at 02:38:06PM +0200, Peter Zijlstra wrote: > If the consumer of the data are RT tasks as well (I hadn't expected that > from a TV capture device) then I'd propose to use FIFO-50 as default. > > The thing is, the moment you're doing actual proper RT, the admin needs > to configure things anyway, which then very much includes setting the > priority of interrupt threads and the like. > > (that is exacty why pretty much everything defaults to FIFO-50) Is the below acceptible? --- Subject: media/ivtv: Reduce default FIFO priority From: Peter Zijlstra Date: Thu Aug 1 12:56:40 CEST 2019 The ivtv driver creates a FIFO-99 thread by default, reduce this to FIFO-50. FIFO-99 is the very highest priority available to SCHED_FIFO and it not a suitable default; it would indicate the ivtv work is the most important work on the machine. Cc: Andy Walls Cc: Mauro Carvalho Chehab Cc: linux-media@vger.kernel.org Cc: linux-kernel@vger.kernel.org Cc: Thomas Gleixner Signed-off-by: Peter Zijlstra (Intel) --- drivers/media/pci/ivtv/ivtv-driver.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/media/pci/ivtv/ivtv-driver.c +++ b/drivers/media/pci/ivtv/ivtv-driver.c @@ -738,7 +738,7 @@ static void ivtv_process_options(struct */ static int ivtv_init_struct1(struct ivtv *itv) { - struct sched_param param = { .sched_priority = 99 }; + struct sched_param param = { .sched_priority = MAX_RT_PRIO / 2 }; itv->base_addr = pci_resource_start(itv->pdev, 0); itv->enc_mbox.max_mbox = 2; /* the encoder has 3 mailboxes (0-2) */