A fix is available
APAR status
Closed as program error.
Error description
On a system with a very heavy exec workload, we can drive very sevear contention on heap 0 xmalloc lock. This is because ncargs by defaul allocates 1MB from the heap which exceeds the nh_balance threshold which by default is 64K. NCARGS should be allocated from the srad heaps as it is a very frequent allocation and it is better to make a change to directly call xmlloc_srad() when we allocate the space for ncargs rather than change the system global threshold as most other allocations of this size tends to be static.
Local fix
There are two possible work arounds: Reduce ncargs : chdev -l sys0 -a ncargs=16 Increase nh_balance : errctrl nh_balance=2097152 -c alloc
Problem summary
On a system with a very heavy exec workload and large number of CPU's, we can drive severe contention on xmalloc lock called in exec path, causing system to get slowdown.
Problem conclusion
Allocate memory from the respective SRAD's for ncargs.
Temporary fix
Comments
6100-07 - use AIX APAR IV52681 6100-08 - use AIX APAR IV53167 6100-09 - use AIX APAR IV51157 6100-09 - use AIX APAR IV51157 6100-09 - use AIX APAR IV51157 7100-01 - use AIX APAR IV50813 7100-02 - use AIX APAR IV50347 7100-03 - use AIX APAR IV51322
APAR Information
APAR number
IV51322
Reported component name
AIX V7.1
Reported component ID
5765H4000
Reported release
710
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Submitted date
2013-10-24
Closed date
2013-10-24
Last modified date
2014-08-14
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
AIX V7.1
Fixed component ID
5765H4000
Applicable component levels
R710 PSY U858978
UP14/05/22 I 1000
PTF to Fileset Mapping
U858978 bos.mp64 7.1.3.15
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Document Information
Modified date:
14 August 2014