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SubjectRe: 2.6.8-rc2-mm2 performance improvements (scheduler?)
Doh. Clipped the paste button on the mouse against the PC just as I
hit send ... pasting a bunch of data in the wrong place ;-) Should've
looked like this:

----------------------------------------------

2.6.8-rc2-mm2 has some significant improvements over 2.6.8-rc2,
particularly at low to mid loads ... at the high loads, it's still
slightly improved, but less significant. Numbers from 16x NUMA-Q.
Kernbench sees most improvement in sys time, but also some elapsed
time ... SDET sees up to 18% more througput.

I'm also amused to see that the process scalability is now pretty
damned good ... a full -j kernel compile (using up to about 1300
tasks) goes as fast as the -j 256 (the middle one) ... and elapsed
is faster than -j16, even if system is a little higher.

I *think* this is the scheduler changes ... fits in with profile diffs
I've seen before ... diffprofiles at the end. In my experience, higher
copy_to/from_user and finish_task_switch stuff tends to indicate task
thrashing. Note also .text.lock.semaphore numbers in kernbench profile.
The SDET one looks like it's load-balancing better (mainly less idle
time).

Great stuff.

M.

Kernbench: (make -j N vmlinux, where N = 2 x num_cpus)
Elapsed System User CPU
2.6.7 45.37 90.91 579.75 1479.33
2.6.8-rc2 45.05 88.53 577.87 1485.67
2.6.8-rc2-mm2 44.09 78.84 577.01 1486.33

Kernbench: (make -j N vmlinux, where N = 16 x num_cpus)
Elapsed System User CPU
2.6.7 44.77 97.96 576.59 1507.00
2.6.8-rc2 44.83 96.00 575.50 1497.33
2.6.8-rc2-mm2 43.43 86.04 576.26 1524.33

Kernbench: (make -j vmlinux, maximal tasks)
Elapsed System User CPU
2.6.7 44.25 88.95 575.63 1501.33
2.6.8-rc2 44.03 87.74 573.82 1503.67
2.6.8-rc2-mm2 43.75 86.68 576.98 1518.00

DISCLAIMER: SPEC(tm) and the benchmark name SDET(tm) are registered
trademarks of the Standard Performance Evaluation Corporation. This
benchmarking was performed for research purposes only, and the run results
are non-compliant and not-comparable with any published results.

Results are shown as percentages of the first set displayed

SDET 1 (see disclaimer)
Throughput Std. Dev
2.6.7 100.0% 1.0%
2.6.8-rc2 95.9% 2.3%
2.6.8-rc2-mm2 111.5% 3.3%

SDET 2 (see disclaimer)
Throughput Std. Dev
2.6.7 100.0% 0.0%
2.6.8-rc2 100.5% 1.4%
2.6.8-rc2-mm2 115.1% 4.0%

SDET 4 (see disclaimer)
Throughput Std. Dev
2.6.7 100.0% 1.0%
2.6.8-rc2 99.2% 1.1%
2.6.8-rc2-mm2 111.9% 0.5%

SDET 8 (see disclaimer)
Throughput Std. Dev
2.6.7 100.0% 0.2%
2.6.8-rc2 100.2% 1.0%
2.6.8-rc2-mm2 117.4% 0.9%

SDET 16 (see disclaimer)
Throughput Std. Dev
2.6.7 100.0% 0.3%
2.6.8-rc2 99.5% 0.3%
2.6.8-rc2-mm2 118.5% 0.6%

SDET 32 (see disclaimer)
Throughput Std. Dev
2.6.7 100.0% 0.3%
2.6.8-rc2 99.7% 0.4%
2.6.8-rc2-mm2 102.1% 0.8%

SDET 64 (see disclaimer)
Throughput Std. Dev
2.6.7 100.0% 0.2%
2.6.8-rc2 101.6% 0.4%
2.6.8-rc2-mm2 103.2% 0.0%

SDET 128 (see disclaimer)
Throughput Std. Dev
2.6.7 100.0% 0.2%
2.6.8-rc2 100.2% 0.1%
2.6.8-rc2-mm2 103.0% 0.3%



Diffprofile for kernbench -j32 (-ve numbers better with mm2)
2135 4.3% default_idle
233 44.2% pte_alloc_one
220 11.9% buffered_rmqueue
164 264.5% schedule
135 5.9% do_page_fault
84 10.7% clear_page_tables
62 62.6% __wake_up_sync
51 60.7% set_page_address
...
-50 -43.9% sys_close
-56 -10.7% __fput
-58 -13.7% set_page_dirty
-61 -10.0% copy_process
-70 -41.4% pipe_writev
-77 -8.1% file_move
-85 -100.0% wake_up_forked_thread
-87 -50.9% pipe_wait
-90 -5.7% path_lookup
-93 -21.2% page_add_anon_rmap
-105 -28.5% release_task
-113 -11.9% do_wp_page
-116 -7.9% link_path_walk
-116 -43.1% pipe_readv
-121 -7.5% atomic_dec_and_lock
-138 -15.4% strnlen_user
-159 -9.4% do_no_page
-167 -2.7% __d_lookup
-214 -59.4% find_idlest_cpu
-230 -6.2% find_trylock_page
-237 -1.6% do_anonymous_page
-255 -7.8% zap_pte_range
-444 -97.6% .text.lock.semaphore
-532 -43.4% Letext
-632 -54.2% __wake_up
-1086 -52.2% finish_task_switch
-1436 -24.6% __copy_to_user_ll
-3079 -46.3% __copy_from_user_ll
-7468 -5.4% total

sdetbench 8 (-ve numbers better with mm2)

...
-58 -33.5% clear_page_tables
-61 -19.3% __d_lookup
-70 -15.2% page_remove_rmap
-71 -71.0% finish_task_switch
-71 -46.4% fput
-72 -56.7% buffered_rmqueue
-73 -53.7% pte_alloc_one
-74 -22.9% __copy_to_user_ll
-75 -31.0% do_no_page
-85 -68.0% free_hot_cold_page
-95 -66.0% __copy_user_intel
-118 -21.1% find_trylock_page
-126 -43.8% do_anonymous_page
-171 -21.6% copy_page_range
-368 -38.8% zap_pte_range
-392 -62.1% do_wp_page
-6262 -11.9% default_idle
-9294 -14.4% total

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