Messages in this thread |  | | Date | Mon, 26 Aug 2002 13:19:24 -0700 | From | "Martin J. Bligh" <> | Subject | Re: [PATCH] tsc-disable_B9 |
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>> It's not correlating it to real time that's the problem. It's getting resceduled >> inbetween calls that hurts. Take your example. >> >> rdtsc >> mov %eax,%ebx >> <- get rescheduled here >> rdtsc >> >> Broken. May even take negative "time". > > Statistically irrelevant. When you have 100,000 samples all the > pre-emption ones drop into the dud sample filter with IRQ disturbance > and so on.
OK, so let's take a better example. People are (I think) mainly using rdtsc to provide a monotonically increasing counter for database "transaction order" stamping. I think that's really the case we're worried about.
M.
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