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=-2.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 3F7FBC433FF for ; Fri, 2 Aug 2019 12:42:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 07BFD2087E for ; Fri, 2 Aug 2019 12:42:03 +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="aRUeVfro" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389572AbfHBMmB (ORCPT ); Fri, 2 Aug 2019 08:42:01 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:40568 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728404AbfHBMl7 (ORCPT ); Fri, 2 Aug 2019 08:41:59 -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=NPQCPXvDjGrvv2bivXcGtX9P+vmLsG3oAEBjoCl8obE=; b=aRUeVfroazA+flrkU5ZsNgcCn 0wd7LYL96qL0vjRya4G83XlluAE2aAqJyRWxeMYddeaA2O8lVlPdDB07jFpUx+0Q9X69Ok9bp6qVS 26X7L38rv+o7FSwL5/o9bq/XGiCK7Gy6MpA9HqG/P9XGlhWYHQMCYb/FvoGhTsjPOWrWoUmcaLmQC dup31zIl4u6D1BIBE6cbLUmNvk0u7KNmkSSIE3ZpDoSefxRSu2s5B6d6O3oheI06TNzcI/J8SMQHM uXY7fsryBs/dNt4RM3blAmQMPLYEiDRQIMYjS/1b+FuOqTdVRowmYXDdyHiZBKoy8f2eATDGe1+kI ysZrE3R/A==; 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 1htWsc-00056T-0E; Fri, 02 Aug 2019 12:41:54 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D0B11202953BA; Fri, 2 Aug 2019 14:41:51 +0200 (CEST) Date: Fri, 2 Aug 2019 14:41:51 +0200 From: Peter Zijlstra To: Qais Yousef Cc: mingo@kernel.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven , Thomas Gleixner Subject: Re: [PATCH 0/5] Fix FIFO-99 abuse Message-ID: <20190802124151.GG2332@hirez.programming.kicks-ass.net> References: <20190801111348.530242235@infradead.org> <20190801131707.5rpyydznnhz474la@e107158-lin.cambridge.arm.com> <20190802093244.GF2332@hirez.programming.kicks-ass.net> <20190802102611.54sae3onftck5fye@e107158-lin.cambridge.arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190802102611.54sae3onftck5fye@e107158-lin.cambridge.arm.com> 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 Fri, Aug 02, 2019 at 11:26:12AM +0100, Qais Yousef wrote: > Yes a somewhat enforced default makes more sense to me. I assume you no longer > want to put the kthreads that just need to be above OTHER in FIFO-1? I'm not sure, maybe, there's not that many of them, but possibly we add another interface for them. > While at it, since we will cram all kthreads on the same priority, isn't > a SCHED_RR a better choice now? I think the probability of a clash is pretty > low, but when it happens, shouldn't we try to guarantee some fairness? It's never been a problem, and aside from these few straggler threads, everybody has effectively been there already for years, so if it were a problem someone would've complained by now. Also; like said before, the admin had better configure. Also also, RR-SMP is actually broken (and nobody has cared enough to bother fixing it).