Messages in this thread | | | Subject | Re: [PATCH]sched: Isochronous class v2 for unprivileged soft rt scheduling | From | "Jack O'Quin" <> | Date | Sun, 06 Feb 2005 21:27:34 -0600 |
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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. -- joq - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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