Werner Almesberger <wa@xxxxxxxxxxxxxxx> 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.
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