Messages in this thread | | | Date | Wed, 25 Feb 2004 23:51:59 +0100 | From | Pavel Machek <> | Subject | Re: [RFC][PATCH] O(1) Entitlement Based Scheduler |
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Hi!
> CPU usage rate caps > ------------------- > > A task's CPU usage rate cap imposes a soft (or hard) upper limit on the rate at > which it can use CPU resources and can be set/read via the files > > /proc/<pid>/cpu_rate_cap > /proc/<tgid>/task/<pid>/cpu_rate_cap > > Usage rate caps are expressed as rational numbers (e.g. "1 / 2") and hard caps > are signified by a "!" suffix. The rational number indicates the proportion > of a single CPU's capacity that the task may use. The value of the number must > be in the range 0.0 to 1.0 inclusive for soft caps. For hard caps there is an > additional restriction that a value of 0.0 is not permitted. Tasks with a > soft cap of 0.0 become true background tasks and only get to run when no other > tasks are active.
Why not use something like percent, parts per milion or whatever?
> When hard capped tasks exceed their cap they are removed from the run queues > and placed in a "sinbin" for a short while until their usage rate decays to > within limits.
How do you solve this one?
I want to kill your system.
I launch task A, "semaphore grabber", that does filesystem operations. Those need semaphores. I run it as "true background".
I wait for A to grab some lock, then I run B, which is while(1);
A holds lock that can not be unlocked, and your system is dead.
This may happen randomly, even without me on your system. Pavel -- When do you have a heart between your knees? [Johanka's followup: and *two* hearts?] - 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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