Messages in this thread | | | Date | Fri, 29 May 2009 08:51:04 +0200 | From | Andi Kleen <> | Subject | Re: comments on Performance Counters for Linux (PCL) |
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> > Take Itanium, it has 4 priv levels and the PMU counters can monitor at > > any priv levels or combination thereof? > > x86 has more priv rings too, but linux only uses 2, kernel (ring 0) and > user (ring 2 iirc). Does ia64 expose more than 2 priv levels in linux?
In a hardware virtualized environment x86 Linux uses at least four.
And yes ia64 also exposes more I believe, e.g. it has the fancy "system calls that run in user context"
-Andi
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