Re: [RFC PATCH] Fair low-latency rwlock v5 (updated benchmarks)

[Mathieu Desnoyers]

Here are some updated benchmarks of the rwlock v5, showing [min,avg,max]
delays in non-contended and contended cases :

The test module is available at :

http://ltt.polymtl.ca/svn/trunk/tests/kernel/test-fair-rwlock.c

** Performance tests

Dual quad-core Xeon 2.0GHz E5405

* Lock contention delays, per context, 60s test

** get_cycles calibration **
get_cycles takes [min,avg,max] 78,79,84 cycles, results calibrated on avg

** Single writer test, no contention **
writer_thread/0 iterations : 964054, lock delay [min,avg,max] 149,157,5933 cycles

** Single reader test, no contention **
reader_thread/0 iterations : 37591763, lock delay [min,avg,max] 59,65,21383 cycles

** Multiple readers test, no contention **
reader_thread/0 iterations : 9062919, lock delay [min,avg,max] 59,921,42593 cycles
reader_thread/1 iterations : 9014846, lock delay [min,avg,max] 59,928,42065 cycles
reader_thread/2 iterations : 9394114, lock delay [min,avg,max] 59,897,46877 cycles
reader_thread/3 iterations : 9459081, lock delay [min,avg,max] 59,896,38207 cycles

** High contention test **
4 thread readers (no delay loop)
2 thread trylock readers (no delay loop)
2 thread writers (10us period)
2 thread trylock writers (10us period)
1 periodical interrupt readers on 7/8 cpus (IPIs).
1 periodical interrupt trylock readers on 7/8 cpus (IPIs).

writer_thread/0 iterations : 2864146, lock delay [min,avg,max] 179,9493,102563 cycles
writer_thread/1 iterations : 2986492, lock delay [min,avg,max] 179,9332,66923 cycles
trylock_writer_thread/0 iterations : 12789892, successful iterations : 3257203
trylock_writer_thread/1 iterations : 12747023, successful iterations : 3268997
reader_thread/0 iterations : 13091562, lock delay [min,avg,max] 59,5806,141053 cycles
reader_thread/1 iterations : 12574027, lock delay [min,avg,max] 59,5706,141839 cycles
reader_thread/2 iterations : 12805706, lock delay [min,avg,max] 59,5738,138725 cycles
reader_thread/3 iterations : 13352731, lock delay [min,avg,max] 59,5606,137585 cycles
trylock_reader_thread/0 iterations : 63135422, successful iterations : 15204229
trylock_reader_thread/1 iterations : 62306024, successful iterations : 15123824
interrupt_reader_thread/0 iterations : 559
interrupt readers on CPU 0, lock delay [min,avg,max] 167,984,16271 cycles
interrupt readers on CPU 1, lock delay [min,avg,max] 179,1185,9125 cycles
interrupt readers on CPU 2, lock delay [min,avg,max] 155,940,8081 cycles
interrupt readers on CPU 3, lock delay [min,avg,max] 83,1158,13355 cycles
interrupt readers on CPU 4, lock delay [min,avg,max] 77,863,6371 cycles
interrupt readers on CPU 5, lock delay [min,avg,max] 173,1169,16331 cycles
interrupt readers on CPU 6, lock delay [min,avg,max] 155,834,8705 cycles
interrupt readers on CPU 7, lock delay [min,avg,max] 173,1159,10115 cycles
trylock_interrupt_reader_thread/0 iterations : 570
trylock interrupt readers on CPU 0, iterations 280, successful iterations : 239
trylock interrupt readers on CPU 1, iterations 590, successful iterations : 538
trylock interrupt readers on CPU 2, iterations 431, successful iterations : 372
trylock interrupt readers on CPU 3, iterations 605, successful iterations : 570
trylock interrupt readers on CPU 4, iterations 659, successful iterations : 570
trylock interrupt readers on CPU 5, iterations 616, successful iterations : 570
trylock interrupt readers on CPU 6, iterations 675, successful iterations : 570
trylock interrupt readers on CPU 7, iterations 597, successful iterations : 561

Mathieu

-- 
Mathieu Desnoyers
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68
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