Significant Memory Reduction Using Huge Page Patch on Database Workload

["Peter Wong" <wpeter@us.ibm.com>]

     (1) 2.5.43-mm2:
         2.5.43 + Andrew Morton's mm2 patch

     (2) 2.5.43-mm2+huge:
         2.5.43 + Andrew Morton's mm2 patch
                + Bill Irwin's hugetlb patch

     Andrew' mm2 patch can be found at:
http://www.zipworld.com.au/~akpm/linux/patches/2.5/2.5.43/2.5.43-mm2/.

     The objective of this comparison is to measure the impact of
Bill's patch. We used 680 for nr_hugepages, ~2.66 GB for the runs.

----------------------------------------------------------------------
System Information:

   - 8-way 700MHz Pentium III Xeon processors, 2MB L2 Cache
   - 4GB RAM
   - 6 SCSI controllers connected to 120 9.1 GB disks with 10K RPM
----------------------------------------------------------------------

     Based upon the performance metrics and CPU utilization, the two
kernels achieve similar performance. However, memory consumption
by rmap and page tables is reduced significantly by using Bill's
patch.


                               2.5.43-mm2         2.5.43-mm2+huge
     ==============================================================
     pte_chain  (max) (MB)        4.3                182.4


     PageTables (max) (MB)        9.5                153.7


     In total, we save ~322 MB in the low memory area.

Regards,
Partha and Peter

Partha Narayanan and Peter Wai Yee Wong
IBM LTC Performance Team
email: wpeter@us.ibm.com


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