Re: 2.6.8-rc2-mm2

Hideo AOKI
2004-08-05T13:00:54Z

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.