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[Xen-ia64-devel] Re: [Xen-devel] [PATCH] nr_cpus calculation problem due

To: beth kon <eak@xxxxxxxxxx>, <Xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-ia64-devel] Re: [Xen-devel] [PATCH] nr_cpus calculation problem due to incorrect sockets_per_node
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Mon, 29 Oct 2007 15:46:23 +0000
Cc: xen-ppc-devel@xxxxxxxxxxxxxxxxxxx, xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
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Thread-topic: [Xen-devel] [PATCH] nr_cpus calculation problem due to incorrect sockets_per_node
User-agent: Microsoft-Entourage/11.3.6.070618
No changes are allowed to the tools interfaces within a stable release
series. It'll be in 3.2.0 in a few weeks time.

 -- Keir

On 29/10/07 15:37, "beth kon" <eak@xxxxxxxxxx> wrote:

> Hi. Wondering if this patch has been reviewed and could be considered
> for inclusion in 3.2. Sorry about the late request. You were asking for
> input last week.
> 
> beth kon wrote:
> 
>> Testing on an 8-node 128-way NUMA machine has exposed a problem with
>> Xen's nr_cpus calculation. In this case, since Xen cuts off recognized
>> CPUs at 32, the machine appears to have 16 CPUs on the first and
>> second nodes and none on the remaining nodes. Given this asymmetry,
>> the calculation of sockets_per_node (which is later used to calculate
>> nr_cpus) is incorrect:
>> 
>> pi->sockets_per_node = num_online_cpus() /(num_online_nodes() *
>> pi->cores_per_socket * pi->threads_per_core);
>> 
>> The most straightforward solution is to remove sockets_per_node, and
>> instead determine nr_cpus directly from num_online_cpus.
>> 
>> This patch has been tested on x86_64 NUMA machines.
>> 
>> ------------------------------------------------------------------------
>> 
>> diff -r b4278beaf354 docs/man/xm.pod.1
>> --- a/docs/man/xm.pod.1 Wed Oct 17 13:12:03 2007 +0100
>> +++ b/docs/man/xm.pod.1 Wed Oct 17 20:09:46 2007 -0700
>> @@ -446,7 +446,6 @@ page more readable):
>>  machine                : i686
>>  nr_cpus                : 2
>>  nr_nodes               : 1
>> - sockets_per_node       : 2
>>  cores_per_socket       : 1
>>  threads_per_core       : 1
>>  cpu_mhz                : 696
>> diff -r b4278beaf354 tools/python/xen/lowlevel/xc/xc.c
>> --- a/tools/python/xen/lowlevel/xc/xc.c Wed Oct 17 13:12:03 2007 +0100
>> +++ b/tools/python/xen/lowlevel/xc/xc.c Wed Oct 17 20:09:46 2007 -0700
>> @@ -721,7 +721,7 @@ static PyObject *pyxc_physinfo(XcObject
>>                             "max_cpu_id",       info.max_cpu_id,
>>                             "threads_per_core", info.threads_per_core,
>>                             "cores_per_socket", info.cores_per_socket,
>> -                            "sockets_per_node", info.sockets_per_node,
>> +                            "nr_cpus",          info.nr_cpus,
>>                             "total_memory",
>> pages_to_kib(info.total_pages),
>>                             "free_memory",
>> pages_to_kib(info.free_pages),
>>                             "scrub_memory",
>> pages_to_kib(info.scrub_pages),
>> diff -r b4278beaf354 tools/python/xen/xend/XendNode.py
>> --- a/tools/python/xen/xend/XendNode.py Wed Oct 17 13:12:03 2007 +0100
>> +++ b/tools/python/xen/xend/XendNode.py Wed Oct 17 20:09:46 2007 -0700
>> @@ -475,7 +475,7 @@ class XendNode:
>> 
>>         cpu_info = {
>>             "nr_nodes":         phys_info["nr_nodes"],
>> -            "sockets_per_node": phys_info["sockets_per_node"],
>> +            "nr_cpus":          phys_info["nr_cpus"],
>>             "cores_per_socket": phys_info["cores_per_socket"],
>>             "threads_per_core": phys_info["threads_per_core"]
>>             }
>> @@ -580,17 +580,9 @@ class XendNode:
>>             str='none\n'
>>         return str[:-1];
>> 
>> -    def count_cpus(self, pinfo):
>> -        count=0
>> -        node_to_cpu=pinfo['node_to_cpu']
>> -        for i in range(0, pinfo['nr_nodes']):
>> -            count+=len(node_to_cpu[i])
>> -        return count;
>> -
>>     def physinfo(self):
>>         info = self.xc.physinfo()
>> 
>> -        info['nr_cpus'] = self.count_cpus(info)
>>         info['cpu_mhz'] = info['cpu_khz'] / 1000
>>         
>>         # physinfo is in KiB, need it in MiB
>> @@ -600,7 +592,6 @@ class XendNode:
>> 
>>         ITEM_ORDER = ['nr_cpus',
>>                       'nr_nodes',
>> -                      'sockets_per_node',
>>                       'cores_per_socket',
>>                       'threads_per_core',
>>                       'cpu_mhz',
>> diff -r b4278beaf354 tools/python/xen/xm/main.py
>> --- a/tools/python/xen/xm/main.py Wed Oct 17 13:12:03 2007 +0100
>> +++ b/tools/python/xen/xm/main.py Wed Oct 17 20:09:46 2007 -0700
>> @@ -1667,9 +1667,8 @@ def xm_info(args):
>>             "release":           getVal(["software_version", "release"]),
>>             "version":           getVal(["software_version", "version"]),
>>             "machine":           getVal(["software_version", "machine"]),
>> -            "nr_cpus":           len(getVal(["host_CPUs"], [])),
>> +            "nr_cpus":           getVal(["cpu_configuration", "nr_cpus"]),
>>             "nr_nodes":          getVal(["cpu_configuration", "nr_nodes"]),
>> -            "sockets_per_node":  getVal(["cpu_configuration",
>> "sockets_per_node"]),
>>             "cores_per_socket":  getVal(["cpu_configuration",
>> "cores_per_socket"]),
>>             "threads_per_core":  getVal(["cpu_configuration",
>> "threads_per_core"]),
>>             "cpu_mhz":           getCpuMhz(),
>> diff -r b4278beaf354 tools/xenmon/xenbaked.c
>> --- a/tools/xenmon/xenbaked.c Wed Oct 17 13:12:03 2007 +0100
>> +++ b/tools/xenmon/xenbaked.c Wed Oct 17 20:09:46 2007 -0700
>> @@ -460,10 +460,7 @@ unsigned int get_num_cpus(void)
>>     xc_interface_close(xc_handle);
>>     opts.cpu_freq = (double)physinfo.cpu_khz/1000.0;
>> 
>> -    return (physinfo.threads_per_core *
>> -            physinfo.cores_per_socket *
>> -            physinfo.sockets_per_node *
>> -            physinfo.nr_nodes);
>> +    return physinfo.nr_cpus;
>> }
>> 
>> 
>> diff -r b4278beaf354 tools/xenstat/libxenstat/src/xenstat.c
>> --- a/tools/xenstat/libxenstat/src/xenstat.c Wed Oct 17 13:12:03 2007 +0100
>> +++ b/tools/xenstat/libxenstat/src/xenstat.c Wed Oct 17 20:09:46 2007 -0700
>> @@ -155,9 +155,7 @@ xenstat_node *xenstat_get_node(xenstat_h
>> }
>> 
>> node->cpu_hz = ((unsigned long long)physinfo.cpu_khz) * 1000ULL;
>> - node->num_cpus =
>> -     (physinfo.threads_per_core * physinfo.cores_per_socket *
>> -      physinfo.sockets_per_node * physinfo.nr_nodes);
>> +        node->num_cpus = physinfo.nr_cpus;
>> node->tot_mem = ((unsigned long long)physinfo.total_pages)
>>    * handle->page_size;
>> node->free_mem = ((unsigned long long)physinfo.free_pages)
>> diff -r b4278beaf354 tools/xentrace/xentrace.c
>> --- a/tools/xentrace/xentrace.c Wed Oct 17 13:12:03 2007 +0100
>> +++ b/tools/xentrace/xentrace.c Wed Oct 17 20:09:46 2007 -0700
>> @@ -309,10 +309,7 @@ unsigned int get_num_cpus(void)
>> 
>>     xc_interface_close(xc_handle);
>> 
>> -    return (physinfo.threads_per_core *
>> -            physinfo.cores_per_socket *
>> -            physinfo.sockets_per_node *
>> -            physinfo.nr_nodes);
>> +    return physinfo.nr_cpus;
>> }
>> 
>> 
>> diff -r b4278beaf354 tools/xm-test/lib/XmTestLib/Xm.py
>> --- a/tools/xm-test/lib/XmTestLib/Xm.py Wed Oct 17 13:12:03 2007 +0100
>> +++ b/tools/xm-test/lib/XmTestLib/Xm.py Wed Oct 17 20:09:46 2007 -0700
>> @@ -218,11 +218,9 @@ def restartXend():
>>         return status
>> 
>> def smpConcurrencyLevel():
>> -    cores = int(getInfo("cores_per_socket"))
>> -    threads = int(getInfo("threads_per_core"))
>> -    sockets = int(getInfo("sockets_per_node"))
>> -
>> -    return cores * sockets * threads
>> +    nr_cpus = int(getInfo("nr_cpus"))
>> +
>> +    return nr_cpus
>> 
>> if __name__ == "__main__":
>>     if isDomainRunning("0"):
>> diff -r b4278beaf354 tools/xm-test/lib/XmTestReport/OSReport.py
>> --- a/tools/xm-test/lib/XmTestReport/OSReport.py Wed Oct 17 13:12:03 2007
>> +0100
>> +++ b/tools/xm-test/lib/XmTestReport/OSReport.py Wed Oct 17 20:09:46 2007
>> -0700
>> @@ -92,7 +92,6 @@ class Machine:
>> 
>>         xenValues = {"nr_cpus"          : "Unknown",
>>                      "nr_nodes"         : "Unknown",
>> -                     "sockets_per_node" : "Unknown",
>>                      "cores_per_socket" : "Unknown",
>>                      "threads_per_core" : "Unknown",
>>                      "cpu_mhz"          : "Unknown",
>> diff -r b4278beaf354 xen/arch/ia64/xen/dom0_ops.c
>> --- a/xen/arch/ia64/xen/dom0_ops.c Wed Oct 17 13:12:03 2007 +0100
>> +++ b/xen/arch/ia64/xen/dom0_ops.c Wed Oct 17 20:09:46 2007 -0700
>> @@ -234,7 +234,7 @@ long arch_do_sysctl(xen_sysctl_t *op, XE
>>     {
>>     case XEN_SYSCTL_physinfo:
>>     {
>> -        int i, node_cpus = 0;
>> +        int i;
>>         uint32_t max_array_ent;
>> 
>>         xen_sysctl_physinfo_t *pi = &op->u.physinfo;
>> @@ -242,18 +242,8 @@ long arch_do_sysctl(xen_sysctl_t *op, XE
>>         pi->threads_per_core = cpus_weight(cpu_sibling_map[0]);
>>         pi->cores_per_socket =
>>             cpus_weight(cpu_core_map[0]) / pi->threads_per_core;
>> +        pi->nr_cpus          = (u32)num_online_cpus();
>>         pi->nr_nodes         = num_online_nodes();
>> -
>> -        /*
>> -         * Guess at a sockets_per_node value.  Use the maximum number of
>> -         * CPUs per node to avoid deconfigured CPUs breaking the average.
>> -         */
>> -        for_each_online_node(i)
>> -            node_cpus = max(node_cpus, cpus_weight(node_to_cpumask(i)));
>> -
>> -        pi->sockets_per_node = node_cpus /
>> -            (pi->cores_per_socket * pi->threads_per_core);
>> -
>>         pi->total_pages      = total_pages;
>>         pi->free_pages       = avail_domheap_pages();
>>         pi->scrub_pages      = avail_scrub_pages();
>> diff -r b4278beaf354 xen/arch/powerpc/sysctl.c
>> --- a/xen/arch/powerpc/sysctl.c Wed Oct 17 13:12:03 2007 +0100
>> +++ b/xen/arch/powerpc/sysctl.c Wed Oct 17 20:09:46 2007 -0700
>> @@ -45,9 +45,7 @@ long arch_do_sysctl(struct xen_sysctl *s
>>             cpus_weight(cpu_sibling_map[0]);
>>         pi->cores_per_socket =
>>             cpus_weight(cpu_core_map[0]) / pi->threads_per_core;
>> -        pi->sockets_per_node = num_online_cpus() /
>> -            (num_online_nodes() * pi->cores_per_socket *
>> pi->threads_per_core);
>> -
>> +        pi->nr_cpus          = (u32)num_online_cpus();
>>         pi->nr_nodes         = num_online_nodes();
>>         pi->total_pages      = total_pages;
>>         pi->free_pages       = avail_domheap_pages();
>> diff -r b4278beaf354 xen/arch/x86/sysctl.c
>> --- a/xen/arch/x86/sysctl.c Wed Oct 17 13:12:03 2007 +0100
>> +++ b/xen/arch/x86/sysctl.c Wed Oct 17 20:09:46 2007 -0700
>> @@ -51,10 +51,8 @@ long arch_do_sysctl(
>>             cpus_weight(cpu_sibling_map[0]);
>>         pi->cores_per_socket =
>>             cpus_weight(cpu_core_map[0]) / pi->threads_per_core;
>> +        pi->nr_cpus = (u32)num_online_cpus();
>>         pi->nr_nodes = num_online_nodes();
>> -        pi->sockets_per_node = num_online_cpus() /
>> -            (pi->nr_nodes * pi->cores_per_socket * pi->threads_per_core);
>> -
>>         pi->total_pages      = total_pages;
>>         pi->free_pages       = avail_domheap_pages();
>>         pi->scrub_pages      = avail_scrub_pages();
>> diff -r b4278beaf354 xen/include/public/sysctl.h
>> --- a/xen/include/public/sysctl.h Wed Oct 17 13:12:03 2007 +0100
>> +++ b/xen/include/public/sysctl.h Wed Oct 17 20:09:46 2007 -0700
>> @@ -79,7 +79,7 @@ struct xen_sysctl_physinfo {
>>     /* IN variables. */
>>     uint32_t threads_per_core;
>>     uint32_t cores_per_socket;
>> -    uint32_t sockets_per_node;
>> +    uint32_t nr_cpus;
>>     uint32_t nr_nodes;
>>     uint32_t cpu_khz;
>>     uint64_aligned_t total_pages;
>>  
>> 
>> ------------------------------------------------------------------------
>> 
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel
>>  
>> 
> 



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