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Bug 1149283

Summary: [vdsm][ppc64] invalid number of processors reported on host
Product: Red Hat Enterprise Virtualization Manager Reporter: Jiri Belka <jbelka>
Component: vdsmAssignee: Vitor de Lima <vdelima>
Status: CLOSED NOTABUG QA Contact: meital avital <mavital>
Severity: medium Docs Contact:
Priority: unspecified    
Version: 3.4.0CC: bazulay, ecohen, gklein, iheim, lpeer, lsurette, michal.skrivanek, oourfali, vdelima, ybronhei, yeylon
Target Milestone: ---   
Target Release: 3.6.0   
Hardware: ppc   
OS: Unspecified   
Whiteboard: virt
Fixed In Version: Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2014-10-08 14:24:27 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1122979    
Attachments:
Description Flags
journalctl output & vdsm.log none

Description Jiri Belka 2014-10-03 16:16:24 UTC 
Created attachment 943757 [details]
journalctl output & vdsm.log

Description of problem:

i have doubts about getVdsCaps output - CPU numbers...

# vdsClient -s 0 getVdsCaps | grep cpu
        cpuCores = '20'
        cpuFlags = 'powernv,model_power8'
        cpuModel = 'POWER8E (raw), altivec supported'
        cpuSockets = '4'
        cpuSpeed = '3458.000000'
        cpuThreads = '20'

cpuThreads seems to be nonsense...

Sep 26 01:50:37 localhost kernel: CPU maps initialized for 8 threads per core.

...
Sep 26 01:50:37 localhost kernel: SLUB: HWalign=128, Order=0-3, MinObjects=0, CPUs=160, Nodes=256
Sep 26 01:50:37 localhost kernel:         RCU restricting CPUs from NR_CPUS=1024 to nr_cpu_ids=160.
...
Sep 26 01:50:37 localhost kernel: Brought up 160 CPUs
Sep 26 01:50:37 localhost kernel: Node 0 CPUs: 0-39
Sep 26 01:50:37 localhost kernel: Node 1 CPUs: 40-79
Sep 26 01:50:37 localhost kernel: Node 16 CPUs: 80-119
Sep 26 01:50:37 localhost kernel: Node 17 CPUs: 120-159
...

thus there is 160 logical cpus.

# grep processor /proc/cpuinfo 
processor       : 0
processor       : 8
processor       : 16
processor       : 24
processor       : 32
processor       : 40
processor       : 48
processor       : 56
processor       : 64
processor       : 72
processor       : 80
processor       : 88
processor       : 96
processor       : 104
processor       : 112
processor       : 120
processor       : 128
processor       : 136
processor       : 144
processor       : 152

IBM Power 8 is 8-thread per core, to there's 20 physical cores.

"S822L: Two 10-core 3.42 GHz or 12-core 3.02 GHz POWER8 processor cards"[1]

(not sure what 'Node' in dmesg means...)

something is wrong as in Admin Portal I see 'CPU Sockets: 4', 'CPU Cores per Socket: 5', 'CPU Threads per Core: 1(SMT Disabled)' for this host.

sockets seems to be wrong in respect to hw specs from ibm site[1], also cores per socket seems wrong[1], and OS boot log (see above) shows thread are enabled... (8).

Version-Release number of selected component (if applicable):
vdsm-4.14.17-1.mrkev.ppc64

How reproducible:
100%

Steps to Reproduce:
1. observe IBM Power8 machine, see boot log (I used journalctl)
2. compare with `vdsClient -s 0 getVdsCaps | grep -i cpu'
3. compare with data in General subtab for Host in Admin Portal

Actual results:
seems wrong

Expected results:
either kernel/ibm is right or vdsm

Additional info:
[1] http://www-03.ibm.com/systems/power/hardware/s812l-s822l/specs.html
Comment 1 Vitor de Lima 2014-10-08 14:23:36 UTC 
PowerKVM hosts must have SMT disabled in order to work, the extra CPU threads are disabled on the fly during the OS boot (in the later stages by the ppc64_cpu command).
Comment 2 Jiri Belka 2014-10-08 14:50:22 UTC 
why /proc/cpuinfo shows 160 logical procs? Seems odd, isn't that base OS bug then?
Comment 3 Jiri Belka 2014-10-08 14:51:34 UTC 
also plz explain:


> something is wrong as in Admin Portal I see 'CPU Sockets: 4', 'CPU Cores per
> Socket: 5', [...] for this host.
Comment 4 Vitor de Lima 2014-10-08 16:45:37 UTC 
Strange, I have checked /proc/cpuinfo and it only shows one enabled thread per core.

Each processor card has two processors:

http://www.ibmsystemsmag.com/linuxonpower/Trends/What-s-New/power8_configurations/

So the topology of the system is: 2 processor cards X 2 processors per card X 5 cores per processor X 1 enabled thread per core
Comment 5 Jiri Belka 2014-10-09 08:28:25 UTC 
> S822L: Two 10-core 3.42 GHz or 12-core 3.02 GHz POWER8 processor cards

ok then, ibm is confusing, i read that as each processor has 10 cores.

thanks for explanation!