Jack O'Quin wrote:
> Werner Almesberger <wa@almesberger.net> writes:
> 
> 
>>[ Cc:s trimmed, added abiss-general ]
>>
>>Con Kolivas wrote:
>>
>>>Possibly reiserfs journal related. That has larger non-preemptible code 
>>>sections.
>>
>>If I understand your workload right, it should consist mainly of
>>computation, networking (?), and disk reads.
> 
> 
> The jack_test3.2 is basically a multiprocess realtime audio test.  A
> fair amount of computation, signifcant task switch overhead, but
> most I/O is to the sound card.
> 
> There's some disk activity starting clients and probably some other
> system activity in the background.
> 
> 
>>I don't know much about ReiserFS, but in some experiments with ext3,
>>using ABISS, we found that a reader application competing with best
>>effort readers would experience worst-case delays of dozens of
>>milliseconds.
>>
>>They were caused by journaled atime updates. Mounting the file
>>system with "noatime" reduced delays to a few hundred microseconds
>>(still worst-case).
> 
> 
> Interesting. Worth a try to verify.  Con was seeing a 6msec delay
> every 20 seconds.  This was devastating to the test, which tries to
> run a full realtime audio cycle every 1.45msec.

They already were mounted noatime :(

Con