Messages in this thread | | | Date | Mon, 02 Jun 2008 11:38:20 +0530 | From | Balbir Singh <> | Subject | Re: [RFC PATCH v1 0/3] Scaled statistics using APERF/MPERF in x86 |
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Pavel Machek wrote: > Hi! > >>> entitlement for the process as per the current CPU frequency. This >>> technique is used in powerpc architecture with the help of hardware >>> registers that accurately capture the entitlement. >>> >> there are some issues with this unfortunately, and these make it >> a very complex thing to do. >> Just to mention a few: >> 1) What if the BIOS no longer allows us to go to the max frequency for >> a period (for example as a result of overheating); with the approach >> above, the admin would THINK he can go faster, but he cannot in reality, >> so there's misleading information (the system looks half busy, while in > > Plus time one-second-computation-job returning anything else is just > wrong. Even when it only happens when overheated... or only on battery > power. > > If you want scaled utime, you need new interface.
We do have a new interface, two new parameters per-task utimescaled and stimescaled. They already exist in task_struct. Ditto for the delay accounting pieces. Did I misunderstand your need for a new interface? We still keep utime and stime around.
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
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