Re: [RFC patch 0/4] TSC calibration improvements

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From: Linus Torvalds
Date: Thursday, September 4, 2008 - 2:52 pm

On Thu, 4 Sep 2008, Alok Kataria wrote:

Why would you? 

The reason the single run completed successfully was apparently that no 
actual virtualization event triggered, so it actually accessed the 
hardware successfully and without any real slowdown.  As shown also by the 
fact that the actual frequency was correct at the end.

The ones that failed presumably all had interrupts that happened in the 
VM, which then immediately triggered the "uhhuh, there was a bump" thing.

IOW, the code worked correctly as designed. It's not a 
"anti-virtualization" feature per se, it's a "detect when virtualization 
screws up timing". When virtualization (or SMI etc) does _not_ screw up 
timing, it all works fine.

			Linus
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Messages in current thread:
[RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Thu Sep 4, 8:18 am)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Thu Sep 4, 8:36 am)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 8:45 am)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Thu Sep 4, 9:00 am)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 9:21 am)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Thu Sep 4, 9:36 am)
Re: [RFC patch 0/4] TSC calibration improvements, Alok Kataria, (Thu Sep 4, 10:39 am)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 10:41 am)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 10:53 am)
Re: [RFC patch 0/4] TSC calibration improvements, Alan Cox, (Thu Sep 4, 11:07 am)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 11:26 am)
Re: [RFC patch 0/4] TSC calibration improvements, H. Peter Anvin, (Thu Sep 4, 11:30 am)
Re: [RFC patch 0/4] TSC calibration improvements, Alok Kataria, (Thu Sep 4, 11:31 am)
Re: [RFC patch 0/4] TSC calibration improvements, H. Peter Anvin, (Thu Sep 4, 11:34 am)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 1:09 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Thu Sep 4, 1:43 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Thu Sep 4, 1:52 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 1:53 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Valdis.Kletnieks, (Thu Sep 4, 2:00 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 2:09 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Thu Sep 4, 2:21 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 2:30 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Thu Sep 4, 2:33 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 2:34 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Alok Kataria, (Thu Sep 4, 2:38 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Thu Sep 4, 2:39 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Thu Sep 4, 2:52 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Alok Kataria, (Thu Sep 4, 3:09 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Alok Kataria, (Fri Sep 5, 3:18 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Fri Sep 5, 3:34 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Sat Sep 6, 1:03 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Sat Sep 6, 1:29 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Sat Sep 6, 1:37 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Sat Sep 6, 1:50 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Sat Sep 6, 1:52 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Sat Sep 6, 1:55 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Sat Sep 6, 1:58 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Sat Sep 6, 1:59 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Sat Sep 6, 2:07 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Sat Sep 6, 2:10 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Sat Sep 6, 2:15 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Sat Sep 6, 2:15 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Sat Sep 6, 2:22 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Sat Sep 6, 2:26 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Thomas Gleixner, (Sat Sep 6, 2:30 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Linus Torvalds, (Sat Sep 6, 2:32 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Ingo Molnar, (Sat Sep 6, 3:40 pm)
Re: [RFC patch 0/4] TSC calibration improvements, Willy Tarreau, (Sat Sep 6, 11:01 pm)