From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from e7.ny.us.ibm.com (e7.ny.us.ibm.com [32.97.182.137]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 5F0761A007F for ; Wed, 17 Sep 2014 05:42:27 +1000 (EST) Received: from /spool/local by e7.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Tue, 16 Sep 2014 15:42:24 -0400 Received: from b01cxnp23032.gho.pok.ibm.com (b01cxnp23032.gho.pok.ibm.com [9.57.198.27]) by d01dlp02.pok.ibm.com (Postfix) with ESMTP id B16626E803F for ; Tue, 16 Sep 2014 15:42:09 -0400 (EDT) Received: from d01av03.pok.ibm.com (d01av03.pok.ibm.com [9.56.224.217]) by b01cxnp23032.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id s8GJgLcH7668040 for ; Tue, 16 Sep 2014 19:42:21 GMT Received: from d01av03.pok.ibm.com (localhost [127.0.0.1]) by d01av03.pok.ibm.com (8.14.4/8.14.4/NCO v10.0 AVout) with ESMTP id s8GJgLGB001109 for ; Tue, 16 Sep 2014 15:42:21 -0400 Message-ID: <5418929C.4050401@linux.vnet.ibm.com> Date: Tue, 16 Sep 2014 14:42:20 -0500 From: Nathan Fontenot MIME-Version: 1.0 To: Nishanth Aravamudan , Benjamin Herrenschmidt Subject: Re: [RFC PATCH] powerpc/numa: add ability to disable and debug topology updates References: <20140909200913.GG22906@linux.vnet.ibm.com> In-Reply-To: <20140909200913.GG22906@linux.vnet.ibm.com> Content-Type: text/plain; charset=utf-8 Cc: linuxppc-dev@lists.ozlabs.org, Paul Mackerras List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 09/09/2014 03:09 PM, Nishanth Aravamudan wrote: > We have hit a few customer issues with the topology update code (VPHN > and PRRN). It would be nice to be able to debug the notifications coming > from the hypervisor in both cases to the LPAR, as well as to disable > reacting to the notifications, to narrow down the source of the > problems. Add a basic level of such functionality, similar to the numa= > command-line parameter. > > Signed-off-by: Nishanth Aravamudan > --- > This is pretty rough, but has been useful in the field already. I'm not > sure if more information would be useful than this basic amount. > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 5ae8608ca9f5..6e3b9e3a2ab4 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -3370,6 +3370,13 @@ bytes respectively. Such letter suffixes can also be entirely omitted. > e.g. base its process migration decisions on it. > Default is on. > > + topology_updates= [KNL, PPC, NUMA] > + Format: {off | debug} > + Specify if the kernel should ignore (off) or > + emit more information (debug) when the > + hypervisor sends NUMA topology updates to an > + LPAR. > + > tp720= [HW,PS2] > > tpm_suspend_pcr=[HW,TPM] > diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c > index d7737a542fd7..72c5ad313cbe 100644 > --- a/arch/powerpc/mm/numa.c > +++ b/arch/powerpc/mm/numa.c > @@ -1160,6 +1160,28 @@ static int __init early_numa(char *p) > } > early_param("numa", early_numa); > > +static int topology_updates_enabled = 1; > +static int topology_updates_debug = 0; > + > +static int __init early_topology_updates(char *p) > +{ > + if (!p) > + return 0; > + > + if (strstr(p, "off")) { > + printk(KERN_INFO "Disabling topology updates\n"); > + topology_updates_enabled = 0; > + } > + > + if (strstr(p, "debug")) { > + printk(KERN_INFO "Enabling topology updates debug\n"); > + topology_updates_debug = 1; > + } > + > + return 0; > +} > +early_param("topology_updates", early_topology_updates); > + > #ifdef CONFIG_MEMORY_HOTPLUG > /* > * Find the node associated with a hot added memory section for > @@ -1546,6 +1568,9 @@ int arch_update_cpu_topology(void) > struct device *dev; > int weight, new_nid, i = 0; > > + if (!topology_updates_enabled) > + return 0; > + > weight = cpumask_weight(&cpu_associativity_changes_mask); > if (!weight) > return 0; > @@ -1610,6 +1635,25 @@ int arch_update_cpu_topology(void) > * > * And for the similar reason, we will skip all the following updating. > */ > + > + if (topology_updates_debug) { > + char *buf = kmalloc_array(NR_CPUS*5, sizeof(char), GFP_KERNEL); > + cpumask_scnprintf(buf, NR_CPUS*5, &updated_cpus); > + printk(KERN_DEBUG "Topology update for the following CPUs:\n"); > + printk(KERN_DEBUG " %s\n", buf); > + printk(KERN_DEBUG "cpumask_weight(&updated_cpus)) = %u\n", > + cpumask_weight(&updated_cpus)); > + > + if (cpumask_weight(&updated_cpus)) { > + for (ud = &updates[0]; ud; ud = ud->next) { > + printk(KERN_DEBUG "cpu %d moving from node %d " > + "to %d\n", ud->cpu, > + ud->old_nid, ud->new_nid); > + } > + } > + kfree(buf); > + } > + > if (!cpumask_weight(&updated_cpus)) > goto out; > > @@ -1807,8 +1851,10 @@ static const struct file_operations topology_ops = { > > static int topology_update_init(void) > { > - start_topology_update(); > - proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops); > + if (topology_updates_enabled) { > + start_topology_update(); > + proc_create("powerpc/topology_updates", 0644, NULL, &topology_ops); > + } > Is there any reason you would want to enable topology updates at some later point? If so you could still create the /proc file and update it to set topology_updates_enabled appropriately in start_topology_update() and stop_topology_update(). -Nathan > return 0; > } > > _______________________________________________ > Linuxppc-dev mailing list > Linuxppc-dev@lists.ozlabs.org > https://lists.ozlabs.org/listinfo/linuxppc-dev >