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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C75B3C19759 for ; Thu, 1 Aug 2019 11:27:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A285E214DA for ; Thu, 1 Aug 2019 11:27:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730864AbfHAL1R (ORCPT ); Thu, 1 Aug 2019 07:27:17 -0400 Received: from mail-wr1-f68.google.com ([209.85.221.68]:40704 "EHLO mail-wr1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725790AbfHAL1R (ORCPT ); Thu, 1 Aug 2019 07:27:17 -0400 Received: by mail-wr1-f68.google.com with SMTP id r1so73157076wrl.7; Thu, 01 Aug 2019 04:27:15 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=JF7ywhFpFNuJZGA1xyx9jGrse3xaPHw4cmSqzNiI3vk=; b=qZrk2KEbitOTgCcaTaW5k/XjAfij/uYC3YNS9eRXlAoSRHb6XF+9oQ8f1nv2cKvF70 msLLtb8OcFSM7qPCZfHi0xvByu9HQlvL5Y4D4opOlkosaa5yB4G19RfZ+udIpbVmtigM qIIvMTIhj6vWJwWNksNYbZONQO/stkZk7chcEPn2XxKZetIrPYxYbw2XmUZGWZ8xCTwZ dnbsCA54YdtCohdcf3wYdSdf5n4rYSkO/GY40R8ZKcLI6RISG2QnzXOzDRiegB/JzpQM NivApK2jHpWsZO8dwMMsMdckwn4pPdlMtndzLhV/xvcMnKEnbErjz+sgNyza0hkAByXZ KCPg== X-Gm-Message-State: APjAAAXpQ9jvbPnK5x6f1GMg/vu8CYvp8MPBQN4IW2ylNCnLrtPZc2OI UFKzwaKMH8cIXygQxU7nmNRPxX+ZPkHCZc15vxQ= X-Google-Smtp-Source: APXvYqzZoh9lq4IJstoOg0/8lFzWL5HjArUiogjMPyBhpEsKUEJr7TttklW94tFumEIQdDSYZ7LjGuimsRYEK9ZHj30= X-Received: by 2002:a5d:4b91:: with SMTP id b17mr1404812wrt.57.1564658835072; Thu, 01 Aug 2019 04:27:15 -0700 (PDT) MIME-Version: 1.0 References: <20190801111348.530242235@infradead.org> <20190801111541.917256884@infradead.org> In-Reply-To: <20190801111541.917256884@infradead.org> From: Geert Uytterhoeven Date: Thu, 1 Aug 2019 13:27:03 +0200 Message-ID: Subject: Re: [PATCH 5/5] spi: Reduce kthread priority To: Peter Zijlstra Cc: Ingo Molnar , Linux Kernel Mailing List , Benson Leung , Enric Balletbo i Serra , Guenter Roeck , Mark Brown , linux-spi Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Peter, On Thu, Aug 1, 2019 at 1:18 PM Peter Zijlstra wrote: > The SPI thingies request FIFO-99 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 SPI work is the > most important work on the machine. > > Cc: Benson Leung > Cc: Enric Balletbo i Serra > Cc: Guenter Roeck > Cc: Mark Brown > Cc: linux-spi@vger.kernel.org > Cc: linux-kernel@vger.kernel.org > Signed-off-by: Peter Zijlstra (Intel) > --- > drivers/platform/chrome/cros_ec_spi.c | 2 +- > drivers/spi/spi.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > --- a/drivers/platform/chrome/cros_ec_spi.c > +++ b/drivers/platform/chrome/cros_ec_spi.c > @@ -706,7 +706,7 @@ static int cros_ec_spi_devm_high_pri_all > struct cros_ec_spi *ec_spi) > { > struct sched_param sched_priority = { > - .sched_priority = MAX_RT_PRIO - 1, > + .sched_priority = MAX_RT_PRIO / 2, include/linux/sched/prio.h says: * Priority of a process goes from 0..MAX_PRIO-1, valid RT * priority is 0..MAX_RT_PRIO-1, and SCHED_NORMAL/SCHED_BATCH * tasks are in the range MAX_RT_PRIO..MAX_PRIO-1. Priority * values are inverted: lower p->prio value means higher priority. So the new 50 is actually a higher priority than the old 99? Given I'm far from an RT expert, I must be missing something? Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds