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=-2.2 required=3.0 tests=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 E3F4BC432C0 for ; Mon, 2 Dec 2019 19:15:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B4430214AF for ; Mon, 2 Dec 2019 19:15:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728040AbfLBTPV (ORCPT ); Mon, 2 Dec 2019 14:15:21 -0500 Received: from mga02.intel.com ([134.134.136.20]:37189 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727730AbfLBTPV (ORCPT ); Mon, 2 Dec 2019 14:15:21 -0500 X-Amp-Result: UNKNOWN X-Amp-Original-Verdict: FILE UNKNOWN X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga101.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 02 Dec 2019 11:15:19 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,270,1571727600"; d="scan'208";a="218430125" Received: from tassilo.jf.intel.com (HELO tassilo.localdomain) ([10.7.201.21]) by fmsmga001.fm.intel.com with ESMTP; 02 Dec 2019 11:15:19 -0800 Received: by tassilo.localdomain (Postfix, from userid 1000) id BF957300B57; Mon, 2 Dec 2019 11:15:19 -0800 (PST) Date: Mon, 2 Dec 2019 11:15:19 -0800 From: Andi Kleen To: Peter Zijlstra Cc: kan.liang@linux.intel.com, mingo@redhat.com, acme@kernel.org, tglx@linutronix.de, bp@alien8.de, linux-kernel@vger.kernel.org, eranian@google.com, alexey.budankov@linux.intel.com, vitaly.slobodskoy@intel.com Subject: Re: [RFC PATCH 3/8] perf: Init/fini PMU specific data Message-ID: <20191202191519.GN84886@tassilo.jf.intel.com> References: <1574954071-6321-1-git-send-email-kan.liang@linux.intel.com> <1574954071-6321-3-git-send-email-kan.liang@linux.intel.com> <20191202124055.GC2827@hirez.programming.kicks-ass.net> <20191202145957.GM84886@tassilo.jf.intel.com> <20191202162152.GG2827@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191202162152.GG2827@hirez.programming.kicks-ass.net> User-Agent: Mutt/1.12.1 (2019-06-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 02, 2019 at 05:21:52PM +0100, Peter Zijlstra wrote: > On Mon, Dec 02, 2019 at 06:59:57AM -0800, Andi Kleen wrote: > > > > > > This is atricous crap. Also it is completely broken for -RT. > > > > Well can you please suggest how you would implement it instead? > > I don't think that is on me; at best I get to explain why it is Normally code review is expected to be constructive. > completely unacceptible to have O(nr_tasks) and allocations under a > raw_spinlock_t, but I was thinking you'd already know that. Ok if that's the only problem then a lock breaker + retry if rescheduling is needed + some limit against live lock should be sufficient. -Andi