On 05/06/2016 03:13 PM, Boris Ostrovsky wrote:
> On 05/06/2016 02:48 PM, Thomas Gleixner wrote:
>> On Fri, 6 May 2016, Joseph Salisbury wrote:
>>> A kernel bug report was opened against Ubuntu [0]. After a kernel
>>> bisect, it was found that reverting the following commit resolved this bug:
>>>
>>> commit 1f12e32f4cd5243ae46d8b933181be0d022c6793
>>> Author: Thomas Gleixner <t...@linutronix.de>
>>> Date: Mon Feb 22 22:19:15 2016 +0000
>>>
>>> x86/topology: Create logical package id
>>>
>>> To build successfully with this commit reverted, I also had to revert
>>> commits: e7ee3e8,2d4de83,87f01cc and 33c3cc7.
>>>
>>> The regression was introduced as of v4.6-rc1.
>>>
>>> I was hoping to get your feedback, since you are the patch author. Do
>>> you think gathering any additional data will help diagnose this issue,
>>> or would it be best to submit a revert request?
>> Yuck. That dies with a divide error. And that looks like XEN is supplying
>> crap
>> data in the CPUID.
> Joe, do you have
>
> ed6069b xen/apic: Provide Xen-specific version of cpu_present_to_apicid
> APIC op
>
> -boris
Yes the commit is in the 4.4 based Ubuntu kernel. This bug also happens
with the vanilla 4.6-rc5 kernel, which also has that commit.
>
>
>> Does the patch below cure the issue?
>>
>> Thanks,
>>
>> tglx
>>
>> 8<---------------
>>
>> --- a/arch/x86/kernel/smpboot.c
>> +++ b/arch/x86/kernel/smpboot.c
>> @@ -332,6 +332,11 @@ static void __init smp_init_package_map(
>> * primary cores.
>> */
>> ncpus = boot_cpu_data.x86_max_cores;
>> + if (!ncpus) {
>> + pr_warn("x86_max_cores == zero !?!?");
>> + ncpus = 1;
>> + }
>> +
>> __max_logical_packages = DIV_ROUND_UP(total_cpus, ncpus);
>>
>> /*
>
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You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/1397880
Title:
[Feature] Memory Bandwidth Monitoring
Status in intel:
New
Status in linux package in Ubuntu:
Fix Released
Status in xen package in Ubuntu:
Fix Released
Status in linux source package in Xenial:
Fix Released
Status in xen source package in Xenial:
Fix Released
Bug description:
Memory Bandwidth Monitoring (MBM) is a CPU feature included in the family of
Platform QoS features. It is used to track memory bandwidth usage for a
specific task, or group of tasks.
Memory Bandwidth Monitoring is an extension of the existing Cache QoS
Monitoring (CQM) feature found in Haswell server. The mechanism used is the
same, where tasks are associated with an Resource Monitoring ID (RMID), which
the CPU uses to track the bandwidth usage.
Upstream status:
Kernel - 4.6
Xen - target 4.6
To manage notifications about this bug go to:
https://bugs.launchpad.net/intel/+bug/1397880/+subscriptions
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