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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 2399AC2D0C1 for ; Fri, 6 Dec 2019 14:17:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EA7B924659 for ; Fri, 6 Dec 2019 14:17:04 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iS/qPmuc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726595AbfLFORD (ORCPT ); Fri, 6 Dec 2019 09:17:03 -0500 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:37816 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726214AbfLFORD (ORCPT ); Fri, 6 Dec 2019 09:17:03 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1575641821; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=AZIJx8+mn7hsmuKsrvwqAWlAV7JzTrtDo1L8YffDmDY=; b=iS/qPmuc+Pz+5nqRceBzKVp+hhjelEMFphYs+E1csNMCKp0DCJWLqWYBF2GdKwaXuiRP/X qPIaUkCIFrvBUbbJsmgEk+Kg2BDG9vAro69B3vlTo8JqSq1N6jdbTSKoBoHzJwVDmGlPRr fnaN+9QaI7pcBcKJYsXk3zImdmvOKz8= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-40-vhicXEh8O6CvUvqBmFTRSw-1; Fri, 06 Dec 2019 09:16:58 -0500 Received: from smtp.corp.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 3256C800D5B; Fri, 6 Dec 2019 14:16:56 +0000 (UTC) Received: from prarit.bos.redhat.com (prarit-guest.7a2m.lab.eng.bos.redhat.com [10.16.222.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 4F86960BF4; Fri, 6 Dec 2019 14:16:54 +0000 (UTC) From: Prarit Bhargava To: prarit@redhat.com Cc: andrea.parri@amarulasolutions.com, brendanhiggins@google.com, gregkh@linuxfoundation.org, john.ogness@linutronix.de, kexec@lists.infradead.org, linux-kernel@vger.kernel.org, peterz@infradead.org, pmladek@suse.com, rostedt@goodmis.org, sergey.senozhatsky@gmail.com, sergey.senozhatsky.work@gmail.com, tglx@linutronix.de, torvalds@linux-foundation.org Subject: Re: [RFC PATCH v5 0/3] printk: new ringbuffer implementation Date: Fri, 6 Dec 2019 09:16:53 -0500 Message-Id: <20191206141653.1199-1-prarit@redhat.com> In-Reply-To: <87zhg6zx31.fsf@linutronix.de> References: <87zhg6zx31.fsf@linutronix.de> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.12 X-MC-Unique: vhicXEh8O6CvUvqBmFTRSw-1 X-Mimecast-Spam-Score: 0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org John Ogness wrote: > Hi Prarit, >=20 > On 2019-12-05, Prarit Bhargava wrote: > > Based on the comments there is going to be a v6 but in any case I am > > starting testing of this patchset on several large core systems across > > multiple architectures (x86_64, ARM64, s390, ppc64le). Some of those > > systems are known to fail boot due to the large amount of printk output= so > > it will be good to see if these changes resolve those issues. >=20 > Right now the patches only include the ringbuffer as a separate entity > with a test module. So they do not yet have any effect on printk. >=20 > If you apply the patches and then build the "modules" target, you will > have a new test_prb.ko module. Loading that module will start some heavy > testing of the ringbuffer. As long as the testing is successful, the > module will keep testing. During this time the machine will be very > slow, but should still respond. >=20 > The test can be stopped by unloading the module. If the test stops on > its own, then a problem was found. The output of the test is put into > the ftrace buffer. >=20 > It would be nice if you could run the test module on some fat machines, > at least for a few minutes to see if anything explodes. ARM64 and > ppc64le will probably be the most interesting, due to memory barrier > testing. >=20 I've run the module overnight on all 4 arches I mentioned above. I didn't see any failures but IIUC the module test runs at max. I'm going to put a load test on these systems that introduces a variable load to interfere with the prbtest module to see if that kicks anything. > Otherwise I will definitely be reaching out to you when we are ready to > perform actual printk testing with the newly agreed up semantics > (lockless, per-console printing threads, synchronous panic > consoles). Thanks for your help with this. > np :) but I should be the one thanking you ;) P. > John Ogness