> First blush is HELL YES! The issue is accounting. When you
> ask how long a program ran, you are looking at the
> accounting that happens on a tick. This is where one of two
Thats also an implementation issue. Note that the current code is also
wildly inaccurate. Mr Shannon says we are good to at best 50 run/sleep
changes a second. I've got "100% busy" workloads that are 99% asleep.
Tracking cpu usage at task switch works a lot better for newer processors
which as well as having rdtsc also have performance counters. In fact you
can do much more interesting things on modern PC class platforms like
scheduling using pre-emption interrupts based on instructions executed,
memory accesses and more.
Alan
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This archive was generated by hypermail 2b29 : Mon Jul 15 2002 - 22:00:20 EST