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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,URIBL_BLOCKED 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 E7A09C0044C for ; Mon, 29 Oct 2018 17:48:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id BFB962080A for ; Mon, 29 Oct 2018 17:48:30 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org BFB962080A Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=davemloft.net 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 S1728157AbeJ3CiH (ORCPT ); Mon, 29 Oct 2018 22:38:07 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:37038 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726532AbeJ3CiH (ORCPT ); Mon, 29 Oct 2018 22:38:07 -0400 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::cf9]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 7309C136DD16E; Mon, 29 Oct 2018 10:48:28 -0700 (PDT) Date: Mon, 29 Oct 2018 10:48:27 -0700 (PDT) Message-Id: <20181029.104827.680192866924184016.davem@davemloft.net> To: kan.liang@linux.intel.com Cc: acme@kernel.org, linux-kernel@vger.kernel.org, wangnan0@huawei.com, jolsa@kernel.org, namhyung@kernel.org, kan.liang@intel.com, ak@linux.intel.com, yao.jin@linux.intel.com, peterz@infradead.org Subject: Re: [PATCHES/RFC] Re: A concern about overflow ring buffer mode From: David Miller In-Reply-To: References: <0247fca0-5a94-9a83-cefa-282804316729@linux.intel.com> <20181029.104008.791032322062574758.davem@davemloft.net> X-Mailer: Mew version 6.7 on Emacs 26 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Mon, 29 Oct 2018 10:48:28 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: "Liang, Kan" Date: Mon, 29 Oct 2018 13:42:56 -0400 > > > On 10/29/2018 1:40 PM, David Miller wrote: >> From: "Liang, Kan" >> Date: Mon, 29 Oct 2018 10:33:06 -0400 >> >>> I just realized that the problem in KNL will be back if we switch >>> back to non-overwrite mode. >> What is KNL? >> > Intel Xeon Phi Processor, Knights Landing. I don't understand how a specific piece of hardware directly leads to ring buffer processing timeouts, or multi-minute thread map processing times... You'll have to explain all of the details of your test scenerio, and the exact problems triggers, which caused you to write these patches which causes serious regressions for what I consider a core simple use case of perf top. And that's running perf top during a parallel kernel build.