[CentOS] Wrties starving reads

[chrism at imntv.com]

Steve Bergman wrote:
> On Wed, 2006-09-13 at 14:29 -0400, chrism at imntv.com wrote:
>
>   
>> What exactly are you doing that's causing this condition?  I've got a 
>> 4-core opteron box that I've just installed 4.4 + updates on and would 
>> like to see if I can duplicate the problem.
>>     
>
> bonnie++ -f
>
> Actually, I'm switching to /home/steve and, as root:
>
> bonnie++ -f -u steve
>
> It's a 4GB machine, so bonnie runs with an 8GB dataset.
>
> I'm installing 4.4 on my desktop box now for testing without raid or
> lvm.
>
> I have an FC5 box at the office which does not exhibit the problem with
> the 2.6.17 kernel using raid1+lvm2.  But the raid is currently running
> in degraded mode.  I'll be syncing up the other drive tonight and will
> test again.
>   
I was using emacs in another window while this was running in another 
console:


Dual Opteron 275 + 2gb RAM + 3Ware9550SX + RAID 10 (8 500gig Barracudas)

Not very pretty but....

[ritz at localhost ~]$ ./bonnie++ -f
Writing intelligently...done
Rewriting...done
Reading intelligently...done
start 'em...done...done...done...
Create files in sequential order...done.
Stat files in sequential order...done.
Delete files in sequential order...done.
Create files in random order...done.
Stat files in random order...done.
Delete files in random order...done.
Version  1.03       ------Sequential Output------ --Sequential Input- 
--Random-
                    -Per Chr- --Block-- -Rewrite- -Per Chr- --Block-- 
--Seeks--
Machine        Size K/sec %CP K/sec %CP K/sec %CP K/sec %CP K/sec %CP  
/sec %CP
localhost.locald 4G           170662  74 64484  20           157369  21 
504.8   1
                    ------Sequential Create------ --------Random 
Create--------
                    -Create-- --Read--- -Delete-- -Create-- --Read--- 
-Delete--
              files  /sec %CP  /sec %CP  /sec %CP  /sec %CP  /sec %CP  
/sec %CP
                 16 +++++ +++ +++++ +++ +++++ +++ +++++ +++ +++++ +++ 
+++++ +++
localhost.localdomain,4G,,,170662,74,64484,20,,,157369,21,504.8,1,16,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++,+++++,+++