From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 26 Mar 2008 07:53:17 +0100 From: Ingo Molnar Subject: Re: [PATCH 09/10] x86: oprofile: remove NR_CPUS arrays in arch/x86/oprofile/nmi_int.c Message-ID: <20080326065317.GH18301@elte.hu> References: <20080325220650.835342000@polaris-admin.engr.sgi.com> <20080325220652.088163000@polaris-admin.engr.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080325220652.088163000@polaris-admin.engr.sgi.com> Sender: owner-linux-mm@kvack.org Return-Path: To: Mike Travis Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Philippe Elie List-ID: * Mike Travis wrote: > Change the following arrays sized by NR_CPUS to be PERCPU variables: > > static struct op_msrs cpu_msrs[NR_CPUS]; > static unsigned long saved_lvtpc[NR_CPUS]; > > Also some minor complaints from checkpatch.pl fixed. thanks, applied. > All changes were transparent except for: > > static void nmi_shutdown(void) > { > + struct op_msrs *msrs = &__get_cpu_var(cpu_msrs); > nmi_enabled = 0; > on_each_cpu(nmi_cpu_shutdown, NULL, 0, 1); > unregister_die_notifier(&profile_exceptions_nb); > - model->shutdown(cpu_msrs); > + model->shutdown(msrs); > free_msrs(); > } > > The existing code passed a reference to cpu 0's instance of struct > op_msrs to model->shutdown, whilst the other functions are passed a > reference to instance of a struct op_msrs. This seemed > to be a bug to me even though as long as cpu 0 and are of > the same type it would have the same effect...? i dont think this has any real effect in practice (the model pointers are not expected to change across cpus on the same system) - but in any case i've promoted your observation to the main portion of the changelog so that we'll have notice of this. (someone might want to play with simulating a weaker CPU on a secondary core, but we've got tons of other assumptions on CPU type symmetry.) Ingo -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org