IBM Power7 Optimization And Tuning Manual page 205

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maxpin%
1
esid_allocator
a. The default value of 1 for esid_allocator enables terabyte segment aliasing, reducing
addressing lookasides. This value can be set to 1 in AIX V6.1 and is suggested for Oracle.
In general, you should use AIX V7.1 defaults for Oracle.
Two noticeable changes from AIX V6.1 to AIX V7.1 are:
The elimination of the lru_file_repage tunable
The default value of 90 for maxpin%, which is increased from 80% in AIX V6.1
Oracle large page usage
Specifications for Oracle large page usage are:
AIX V6.1 and AIX V7.1 support three or four page sizes, depending on the hardware: 4 KB
(default), 64 KB, 16 MB, and 16 GB. All four page sizes are supported by Power Systems
from POWER5+ firmware level 240-202 onward.
Page sizes 64 KB and 16 MB benefit Oracle performance by reducing kernel lookaside
processing to resolve virtual to physical addresses. Oracle 11g uses 64 KB pages for data
spaces by default.
LOCK_SGA = FALSE:
– This setting is the default, which means that the SGA is not pinned in memory.
– In general, you should not pin SGA.
– Automatic Memory Management (AMM) uses 64 KB pages for SGA if memory
is available.
This value is the preferred one
–
same performance benefit as 16 MB pages and require no special management.
– Oracle 10.2.0.4 with Oracle patch 7226548 also uses 64 KB pages for the SGA.
LOCK_SGA = TRUE:
– The AIX parameters to enable pinned memory and 16 MB large pages are:
• vmo –p –o v_pinshm=1 (allows pinned memory and requires reboot)
• vmo –p –o lgpg_size=16777216 -o lgpg_regions=number_of_large_pages, where
number_of_large_pages=INT[SGA size -1)/16MB)]+1
– AMM can be used with pinned 16 MB pages, provided the formula for calculating the
number of large pages is modified so that the number of large
pages=memory_max_target+1.
– The capabilities that are required to allow Oracle to use 16 MB large pages (implement
as root) can be set by running the following command:
#chuser capabilities=CAP_BYPASS_RAC_VMM,CAP_PROPAGATE oracle
For more information, go to
http://www.ibm.com/developerworks/forums/servlet/JiveServlet/download/747-31
3057-14417535-361419/Oracle_Tuning_on_AIX.pdf
– With Oracle 10.2.0.4, patch 7226548 is also required to use 16 MB pinned pages.
Using 64 KB pages for data, text, and stack regions (applies to Oracle 10.2.0.4 as well):
– 64 KB page size for data, text, and stack regions is useful in environments with a large
(for example. 64 KB+) SGA and many online transaction processing (OLTP) users. For
smaller Oracle instances, 4 KB is sufficient for data, text, and stack.
Appendix C. POWER7 optimization and tuning with third-party applications
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a
, as it has been found that 64 KB pages yield nearly the
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and click metalink note: 372157.1
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