Re: [PATCH]sched: Isochronous class v2 for unprivileged soft rt scheduling

[Werner Almesberger]

[ 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.

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).

- Werner

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 / Werner Almesberger, Buenos Aires, Argentina         wa@xxxxxxxxxxxxxxx /
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