Messages in this thread | | | Subject | Re: [RFCv6 PATCH 09/10] sched: deadline: use deadline bandwidth in scale_rt_capacity | From | Luca Abeni <> | Date | Mon, 14 Dec 2015 15:38:53 +0100 |
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On 12/14/2015 03:02 PM, Vincent Guittot wrote: [...] >>>> Small nit: why "average" utilization? I think a better name would be >>>> "runqueue utilization" >>>> or "local utilization", or something similar... If I understand correctly >>>> (sorry if I >>>> missed something), this is not an average, but the sum of the >>>> utilisations >>>> of the tasks >>>> on this runqueue... No? >>> >>> >>> I have used "average" because it doesn't reflect the active/actual >>> utilization of the run-queue but the forecasted average bandwidth of >>> the CPU that will be used by deadline task. >> >> Well, this is just nitpicking, so feel free to ignore (I just mentioned >> this point because I was initially confused by the "average" name). But I >> think this is "maximum", or "worst-case", not "average", because (as far >> as I can understand) this field indicates that SCHED_DEADLINE tasks will >> not be able to consume more than this fraction of CPU (if they try to >> consume more, the scheduler throttles them). >> >>> I'm open to change the name if another one makes more sense >> >> In real-time literature this is often called simply "utilization" (or >> "worst-case >> utilization" by someone): when a task can have a variable execution time, >> its >> utilization is defined as WCET (maximum execution time) / period. > > ok. Let follow real-time literature wording and remove "average" to > keep only utilization. > so the variable will be named: > > s64 util_bw; Well, "utilization" and "bandwidth" are often used to indicate the same quantity, so "util_bw" sounds strange. I'd call it simply "utilization" or "bandwidth" (otherwise, just leave the name as it is... I said this is just nitpicking).
Luca
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