Re: 2.6.8-rc2-mm2

[Hideo AOKI]

I also tested --mm kernels for no thrashing situation by our benchmark
suit.

In 2.6.8-rc2-mm2, overhead of page_refernced_one() decreases in shared
memory access. Additionally, it seems that token based thrashing
control patch has not bad effect in no thrashing situation.


** Overview of workload

Benchmark program creates workload processes that alternate disk IO
with shared memory access.



** Detailed environment of performance evaluation

- Hardware
  CPU: Xeon 1.6GHz * 4
  Memory: 4GB
  HDD: IDE ATA100 

- The benchmark suit
  The benchmark suit is the wblg-disk 1.0.2, which I have released on
  SourceForge. You can get from following URL.


  <http://sourceforge.net/project/showfiles.php?group_id=110454&package_id=119281>. 

- Configuration of benchmark suit
  + number of workload process: 640 processes
  + read/write ratio: read 0% / write 100%
  + file IO size: 1KB - 256KB (random) 

  + Shard memory regions: 1.6GB * 1 
    All workload processes share one shared memory region.
  + Each process repeats 4 byte memory access each 4KB.

  Measurement time: 3 hour
  Measurement items: write throughput

- Other configurations
  Using Oprofile 
  Issue vmstat command each 1 minute


** Results of performance evaluation

* result of benchmark
                       write throughput [MB/s]
       2.6.8-rc2-mm1:  2.08
       2.6.8-rc2-mm2:  2.10

* result of vmstat
                       swap in (min-max)(kB/s) swap out (min-max)(kB/s)
       2.6.8-rc2-mm1:  0 - 9                   0 - 9         
       2.6.8-rc2-mm2:  0 - 1                   0 - 1         

* Results of Oprofile

 - system profiling (top 2)

   2.6.8-rc2-mm1:
       No.     samples         %               
       1       252096016       81.1833 wblg-disk_client
       2        55708450       17.94   vmlinux-2.6.8-rc2-mm1

   2.6.8-rc2-mm2:
       No.     samples         %
       1       180452715       84.9684 wblg-disk_client
       2        29715808       13.9921 vmlinux-2.6.8-rc2-mm2

 - kernel profiling (top 10) 

   Ratio of page_referenced_one() and kmap_atomic() decreased. Ratio
   of copy_page_range(), page_fault(), and refill_inactive_zone()
   increased.

   2.6.8-rc2-mm1:
       No.     samples         %       symbol name
       1       24952210        44.7907 page_referenced_one
       2        6924133        12.4292 kmap_atomic
       3        2751806         4.9397 flush_tlb_page
       4        1466868         2.6331 copy_page_range
       5        1362218         2.4453 try_atomic_semop
       6        1042919         1.8721 mark_offset_tsc
       7         820792         1.4734 page_fault
       8         633105         1.1365 vma_prio_tree_next
       9         586925         1.0536 update_queue
       10        576520         1.0349 __copy_from_user_ll

   2.6.8-rc2-mm2:
       No.     samples         %       symbol name
       1       10778546        36.2721 page_referenced_one
       2        2821678         9.4955 kmap_atomic
       3        1526580         5.1373 copy_page_range
       4        1400807         4.714  flush_tlb_page
       5         753029         2.5341 mark_offset_tsc
       6         724207         2.4371 page_fault
       7         461152         1.5519 refill_inactive_zone
       8         436286         1.4682 __copy_from_user_ll
       9         395080         1.3295 ext3_find_entry
       10        341127         1.148  apic_timer_interrupt

Best regards,
Hideo AOKI

Systems Development Laboratory, Hitachi, Ltd.


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