Opened 16 years ago
Last modified 4 years ago
#1993 new enhancement
Implement using HPET timers and other mechanisms than TSC for time keeping — at Version 1
| Reported by: | axeld | Owned by: | axeld |
|---|---|---|---|
| Priority: | normal | Milestone: | R1.1 |
| Component: | System/Kernel | Version: | |
| Keywords: | Cc: | leavengood@… | |
| Blocked By: | Blocking: | ||
| Platform: | All |
Description (last modified by )
On CPUs that are able to change their frequency, the TSC increment is not invariant. Therefore, we cannot use it to compute time on these machines. Unfortunately, most recent CPUs are affected due to power saving features.
Furthermore, in a SMP environment, the TSC of the different CPUs can drift apart. See http://lkml.org/lkml/2005/11/4/173 for an interesting insight on that topic.
For HPET (and PM timer) see ACPI 3.0 specification: http://www.acpi.info/spec.htm
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