rwsem benchmarks [Re: generic rwsem [Re: Alpha "process table hang"]]

[D . W . Howells]

You asked for some benchmarks Andrea, so I've obtained some.

The set of test modules can be found at:

        ftp://infradead.org/pub/people/dwh/rwsem-test.tar.bz2

(This also includes rwsem-stat.txt which has a copy of the benchmark results 
in as well)

There are six test programs. They can be made for i386 by the following 
command:

        make

And can also be made to invoke the scheduler after each pass through the loop:

        make SCHED=yes

I ran each individual test twice, hence the two sets of results for 
permutation.

My machine is a Dual 400MHz PII with an 440BX chipset. All the tests were run 
in runlevel 3 with no other applications running.

I benchmarked four different environments:

        (1) 2.4.4-pre3 + Andrea's generic rwsem patch
        (2) 2.4.4-pre4 using XADD to implement the rwsems
        (3) same as (2) but with a tweak to make rwsem_wake() less fair
        (4) 2.4.4-pre3 using my generic spinlock code to implement the rwsems

David


TEST            NUM READERS     NUM WRITERS     CONTENTION
=============== =============== =============== ==========
rwsem-rw        4               2               r-w & w-w
rwsem-ro        4               0               no
rwsem-wo        0               4               w-w only
rwsem-r1        1               0               no
rwsem-w1        0               1               no
rwsem-r2        2               0               no


ENVIRONMENT                     TEST    SCHED   READERS         WRITERS
=============================== ======= ======= =============== =======
Linux-2.4.4-pre3 + AA-rwsem     rws-rw  no       3330281            1009
                                                 3331972             994
                                        yes      1767102          607091
                                                 1743420          642095
                                rws-ro  no       2534630        n/a
                                                 3535202        n/a
                                        yes      2837218        n/a
                                                 3164814        n/a
                                rws-wo  no      n/a              2507449
                                                n/a              2399102
                                        yes     n/a              1568467
                                                n/a              1412262
                                rws-r1  no       9232485        n/a
                                                 9217585        n/a
                                        yes      5483757        n/a
                                                 5487028        n/a
                                rws-w1  no      n/a              9900333
                                                n/a              9918021
                                        yes     n/a              5745657
                                                n/a              5747063
                                rws-r2  no       3499275        n/a
                                                 3518590        n/a
                                        yes      3184431        n/a
                                                 3180287        n/a

------------------------------- ------- ------- --------------- -------
Linux-2.4.4-pre4 [XADD]         rws-rw  no        563388          283005
                                                  558159          280288
                                        yes       683670          197017
                                                  700714          194316
                                rws-ro  no       6316985        n/a
                                                 6314241        n/a
                                        yes      4309406        n/a
                                                 4575043        n/a
                                rws-wo  no      n/a               765699
                                                n/a               763876
                                        yes     n/a               650512
                                                n/a               652287
                                rws-r1  no      15171532        n/a
                                                15158899        n/a
                                        yes      7222310        n/a
                                                 7229793        n/a
                                rws-w1  no      n/a             13942744
                                                n/a             13991823
                                        yes     n/a              7362605
                                                n/a              7356127
                                rws-r2  no       5517671        n/a
                                                 5516168        n/a
                                        yes      3452796        n/a
                                                 3331947        n/a

------------------------------- ------- ------- --------------- -------
Linux-2.4.4-pre4 [XADD]         rws-rw  no        531929          267129
 + slightly-unfair-contention                     531093          266822
   tweak                                yes       839560          185670
                                                  903995          183958
                                rws-ro  no       6318293        n/a
                                                 6320336        n/a
                                        yes      4257862        n/a
                                                 4315243        n/a
                                rws-wo  no      n/a               766427
                                                n/a               766471
                                        yes     n/a               644036
                                                n/a               642236


------------------------------- ------- ------- --------------- -------
Linux-2.4.4-pre4 [GENERIC-SPIN] rws-rw  no        545138          274002
                                                  545378          273785
                                        yes       755343          187874
                                                  745888          185562
                                rws-ro  no       4500398        n/a
                                                 4506583        n/a
                                        yes      3137883        n/a
                                                 3129119        n/a
                                rws-wo  no      n/a               763599
                                                n/a               763059
                                        yes     n/a               641256
                                                n/a               647319
                                rws-r1  no      13110083        n/a
                                                13115436        n/a
                                        yes      6950687        n/a
                                                 6951901        n/a
                                rws-w1  no      n/a             13004627
                                                n/a             13003754
                                        yes     n/a              6899764
                                                n/a              6898953
                                rws-r2  no       4741615        n/a
                                                 4746860        n/a
                                        yes      3340292        n/a
                                                 2967268        n/a
0ãA8

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