Messages in this thread | | | From | Justin TerAvest <> | Date | Thu, 24 Mar 2011 19:38:50 -0700 | Subject | Why do we use cpu nice priority for ioprio? |
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It's not clear why the cpu nice value should be mapped to the ioprio for a task when none is picked.
Internally, at cfq_init_prio_data(), we just set: ioprio = IOPRIO_NORM; ioprio_class = IOPRIO_CLASS_BE; if ioprio_class is IOPRIO_CLASS_NONE.
The problem is that today, SCHED_RR and SCHED_FIFO threads automatically get bumped up to RT class. This all happens behind the curtains and the io_class of the thread is still shown as NONE with sys_ioprio_get(). What's the motivation behind this promotion of ioprio class?
I'd be happy to send a patch to change the behavior, but I'm curious why the code promotes based on task nice values today.
Thanks!
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