Messages in this thread | | | From | schwidefsky@de ... | Date | Tue, 10 Apr 2001 13:38:43 +0200 | Subject | Re: No 100 HZ timer ! |
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>> Just how would you do kernel/user CPU time accounting then ? It's currently done >> on every timer tick, and doing it less often would make it useless. > >On the contrary doing it less often but at the right time massively improves >its accuracy. You do it on reschedule. An rdtsc instruction is cheap and all >of a sudden you have nearly cycle accurate accounting If you do the accounting on reschedule, how do you find out how much time has been spent in user versus kernel mode? Or do the Intel chips have two counters, one for user space execution and one for the kernel?
blue skies, Martin
Linux/390 Design & Development, IBM Deutschland Entwicklung GmbH Schönaicherstr. 220, D-71032 Böblingen, Telefon: 49 - (0)7031 - 16-2247 E-Mail: schwidefsky@de.ibm.com
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