From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id DBB8B1A00FF for ; Wed, 17 Sep 2014 13:38:30 +1000 (EST) Message-ID: <1410925110.1586.3.camel@concordia> Subject: Re: [RFC PATCH] powerpc/numa: add ability to disable and debug topology updates From: Michael Ellerman To: Nishanth Aravamudan Date: Wed, 17 Sep 2014 13:38:30 +1000 In-Reply-To: <20140915235455.GB5238@linux.vnet.ibm.com> References: <20140909200913.GG22906@linux.vnet.ibm.com> <1410757536.32643.1.camel@concordia> <20140915235455.GB5238@linux.vnet.ibm.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Cc: Paul Mackerras , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Mon, 2014-09-15 at 16:54 -0700, Nishanth Aravamudan wrote: > On 15.09.2014 [15:05:36 +1000], Michael Ellerman wrote: > > On Tue, 2014-09-09 at 13:09 -0700, Nishanth Aravamudan wrote: > > > Does it really need to be a boot param, or could it be a debugfs or > > sysctl flag? ie. do we need to disable it immediately at boot or would > > it be OK if it was /etc/rc.local or similar that turned it off ? > > We need it off at boot, potentially. An LPAR does not indicate that it > will or will not respond to the events in any synchronous fashion, so > the hypervisor is free to send them to us whenever. OK. I guess we're stuck with a boot time parameter for on/off then. > > As far as the debug goes, we could just use pr_debug() with > > CONFIG_DYNAMIC_DEBUG, it's not quite as easy to enable as a kernel > > parameter but for the odd bit of debugging it should be fine. > > That's a good point, I wonder with that mechanism if we should perhaps > extend/remove other static debugging methods in favor of that (e.g., > numa=debug)? Yes definitely. It's slightly more arcane to enable, ie. to turn on dynamic debugging in numa.c at boot your command line needs: dyndbg="file numa.c +p" But that's fine unless it's an option you expect users to be using regularly which none of these are. cheers