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_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS,T_DKIM_INVALID, USER_AGENT_MUTT 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 60E3AC468C6 for ; Thu, 19 Jul 2018 20:31:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0DEDC2084E for ; Thu, 19 Jul 2018 20:31:28 +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="SPrDf8e7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 0DEDC2084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730144AbeGSVQL (ORCPT ); Thu, 19 Jul 2018 17:16:11 -0400 Received: from bombadil.infradead.org ([198.137.202.133]:46984 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727769AbeGSVQK (ORCPT ); Thu, 19 Jul 2018 17:16:10 -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=0j69lDSxJE6g6prtT5F3TYNRStuPMqOk5KNLppvYte4=; b=SPrDf8e7cdkMnTrlxBDtLRzxu Y6ToCckFOtPgl4j/NlWqlIydKMm1yu3PjE/Ablc+SlyYMFzBxwvMtZIU7uawOwgUp4ySB/KcqwPpN /MeI1pxNuEKljrR89mTFCPYGsgEt5HzVypeInjSGZwyEINMXVCCx1narj+09X8/BZDRrDockerrhu Uzopnjgpn8nc18AjMk7k/jodFMVx4jtblDH/GZqGwahOpQacuxAh7ulxc2VJd4r6Jfi5sMAYU7Qdc 9VT8HHAPW4ZBVz/vZ5MevhUEaT+N/s8pet8H3K+GkNyL8eANOojnr0vyC8TXijg0L7WeX54TnJlqv aJfI8P06g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=hirez.programming.kicks-ass.net) by bombadil.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1fgFa1-0002G6-L0; Thu, 19 Jul 2018 20:31:17 +0000 Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 083E420275F38; Thu, 19 Jul 2018 22:31:15 +0200 (CEST) Date: Thu, 19 Jul 2018 22:31:15 +0200 From: Peter Zijlstra To: Johannes Weiner Cc: Ingo Molnar , Andrew Morton , Linus Torvalds , Tejun Heo , Suren Baghdasaryan , Vinayak Menon , Christopher Lameter , Mike Galbraith , Shakeel Butt , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH 08/10] psi: pressure stall information for CPU, memory, and IO Message-ID: <20180719203114.GL2494@hirez.programming.kicks-ass.net> References: <20180712172942.10094-1-hannes@cmpxchg.org> <20180712172942.10094-9-hannes@cmpxchg.org> <20180718120318.GC2476@hirez.programming.kicks-ass.net> <20180719184740.GA26291@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180719184740.GA26291@cmpxchg.org> User-Agent: Mutt/1.10.0 (2018-05-17) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 19, 2018 at 02:47:40PM -0400, Johannes Weiner wrote: > On Wed, Jul 18, 2018 at 02:03:18PM +0200, Peter Zijlstra wrote: > > On Thu, Jul 12, 2018 at 01:29:40PM -0400, Johannes Weiner wrote: > > > + /* Update task counts according to the set/clear bitmasks */ > > > + for (to = 0; (bo = ffs(clear)); to += bo, clear >>= bo) { > > > + int idx = to + (bo - 1); > > > + > > > + if (tasks[idx] == 0 && !psi_bug) { > > > + printk_deferred(KERN_ERR "psi: task underflow! cpu=%d idx=%d tasks=[%u %u %u] clear=%x set=%x\n", > > > + cpu, idx, tasks[0], tasks[1], tasks[2], > > > + clear, set); > > > + psi_bug = 1; > > > + } > > > > WARN_ONCE(!tasks[idx], ...); > > It's just open-coded because of the printk_deferred, since this is > inside the scheduler. Yeah, meh. There's ton of WARNs in the scheduler, WARNs should not trigger anyway. But yeah printk is crap, which is why I don't use printk anymore: https://lkml.kernel.org/r/20170928121823.430053219@infradead.org