L4Linux-2.6.14 perfomance question

Der Herr Hofrat der.herr at hofr.at
Wed Dec 7 21:39:04 CET 2005

HI !

 I'm very new to L4Linux so my question might be obvious - anyway did not
 find anything directly related in the archive. For a start I did a quick
 performance comparison using lmbench-3.0.

 This comparison is based on the L4Linux-2.6 running a debina ramdisk
 lmbench-3.0 vs Linux-2.6.14 running from harddisk (though data files
 were in tempfs in both cases - so the HD should not really have much
 of an impact). 

          L4Linux     Linux 2.6.14

com lat.: (us)
lat_pipe  14.1-14.5       2.0 
lat_fifo  13.9-14.6       2.2
lat_unix  19.4-19.5       3.2
lat_sem    3.5            0.6

lat_proc: (us)
    fork  805-1249       80-82
    exec 3124-3784      212-230
   shell 9992-9997     2480-2592

tlb:      7,8,32       always 32

bw com: (MB/s)
bw_pipe  921-958       1338-1352
bw_unix  429-753       1122-1138

lat mem: oopses under L4Linux - no results 

bw_mem: (MB/s)
 bcopy  3856-4066      5056-5080
  rdwr 11937-13242       16052
syscall: (us)
   null  2.4-2.8          0.13
   read  2.6-3.3       0.26-0.31 
   stat  4.4-4.9          0.89
   open  6.5-8.1       1.16-1.39

The thing that supprises me is that the performance variation is much 
higher than on regular linux - in both cases the system was idle except
for lmbench running, so I'm excluding any syslog parties or cron jobs
fireing at inconvenient times (i.e bandwidth of UNIX sockets has a variance
of almost 50% ?). Generally the performance difference is much larger
than I would have expected, especially also in areas where I don't quite
understand where the u-kenrel can impact the Linux system (i.e. bcopy,
memory read-write)

Are these values in the usual range or did I screw up fundamentally ?

thx !
Prof. Nicholas Mc Guire                               University of Lanzhou
Distributed & Embedded System Lab                   http://dslab.lzu.edu.cn
School of Information Science and Engeneering            mcguire at lzu.edu.cn 
Tianshui South Road 222. Lanzhou 730000                          .P.R.China
Tel:+86-931-8912025                                     Fax:+86-931-8912022
Lichtensteinstr. 31, Mistelbach A-2130                              Austria 
Tel:+43-2572-201082                                     Fax:+43-2572-201084

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