Why is MySQL nearly twice as fast on Linux/AMD64 Vs.FreeBSD/AMD64?

[JG]

Compare the last set of benchmarks to these new ones.

Using Linux Mandrake64 and super-smack:



--------------------------------------------------------------------
SERVER CONFIG:

** Mandrake64 64-bit**

SMP Mon Apr 19 10:48:13 CEST 2004 x86_64 unknown unknown GNU/Linux
2.6.3-9mdksmp

MySQL:  Ver 4.0.18 for mandrake-linux-gnu on x86_64 (Source distribution)

[root at amd64m]# ldd /usr/sbin/mysqld
         librt.so.1 => /lib64/tls/librt.so.1 (0x0000002a9566d000)
         libdl.so.2 => /lib64/libdl.so.2 (0x0000002a95786000)
         libz.so.1 => /lib64/libz.so.1 (0x0000002a9588a000)
         libcrypt.so.1 => /lib64/libcrypt.so.1 (0x0000002a9599d000)
         libnsl.so.1 => /lib64/libnsl.so.1 (0x0000002a95ad0000)
         libpthread.so.0 => /lib64/tls/libpthread.so.0 
(0x0000002a95be8000)   <-- eh?
         libstdc++.so.5 => /usr/lib64/libstdc++.so.5 (0x0000002a95cfc000)
         libm.so.6 => /lib64/tls/libm.so.6 (0x0000002a95eda000)
         libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x0000002a96033000)
         libc.so.6 => /lib64/tls/libc.so.6 (0x0000002a9613e000)
         /lib64/ld-linux-x86-64.so.2 => /lib64/ld-linux-x86-64.so.2 
(0x0000002a95556000)

---------------------------------------------------------------------
Each benchmark ran 4 times and highest was shown.
---------------------------------------------------------------------


REMOTE (Over 100mbit LAN dc0 to bge0):


- Using "Stock" Mandrake64 Install,  without my.cnf

devbox# super-smack update-select.smack 30 10000
Query Barrel Report for client smacker
connect: max=65ms  min=8ms avg= 20ms from 30 clients
Query_type      num_queries     max_time        min_time        q_per_s
select_index    300000  4       0       4441.59
update_index    300000  1       0       4441.59


- Using "Stock" Mandrake64 Install,  with my-huge.cnf
   but it compiled about max_connections @ 512 and dropped them to 457...

040521  1:17:42  Warning: setrlimit couldn't increase number of open files 
to more than 1024 (request: 1134)
040521  1:17:42  Warning: Changed limits: max_connections: 
100  table_cache: 457

devbox# super-smack update-select.smack 30 10000
Query Barrel Report for client smacker
connect: max=65ms  min=0ms avg= 21ms from 30 clients
Query_type      num_queries     max_time        min_time        q_per_s
select_index    300000  5       0       4296.86
update_index    300000  15      0       4296.86


So the results above were the best so far.
Strange that using the my-huge.cnf would produce worse results.
I guess that's a question for the Mandrake list though.


Anyway, the closest FreeBSD came so far was under 32-bit i386 (on AMD64 
hardware) :-(

- Using my-huge.cnf
- Using SCHED_4BSD kernel
- Using mysql compiled with linuxthreads
- (see a couple posts back for complete details)

devbox# super-smack update-select.smack 30 10000
Query Barrel Report for client smacker
connect: max=817ms  min=37ms avg= 326ms from 30 clients
Query_type      num_queries     max_time        min_time        q_per_s
select_index    300000  	2       	0       	3718.13
update_index    300000  	9       	0       	3718.13