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[Xen-bugs] [Bug 537] Xen0 bogomips has a lot of differences with Native

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Subject: [Xen-bugs] [Bug 537] Xen0 bogomips has a lot of differences with Native Linux.
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Date: Fri, 17 Feb 2006 01:33:00 +0000
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------- Additional Comments From yongkang.you@xxxxxxxxx  2006-02-17 01:33 
After I change the CONFIG_HZ from 250 to 100. The bogomips drops too. It is 
more close to the Native Linux. Its now 6002.90 (Native is 5980.16). The 
Native Linux kernel is 2.6.9.

The old 2.6 kernel default HZ should be set to 1000, am I right? So why should 
latest Xen0 set 100, it will get more close bogomips with native Linux.

But I found if I set the CONFIG_HZ to 100. Xen0 Linux interrupts number will 
lost many, I use `cat /proc/interrupts|grep timer; sleep 10; 
cat /proc/interrupts|grep timer` to count interrupts number between 10 
seconds. I only catch 300 times interrupt when I run above script. I think it 
should be 1000 (100 interrupts/sec x 10 secs). BTW, my Xen0 is SMP enabled. I 
count 2 CPUs interrupts together. 

And I found the interrupts number of 10 seconds doesn't change, no matter 
HZ=250 or 100. It is always 300 (I run a lot of time). E.g.

[root@vt-yyou ~]# cat /proc/interrupts |grep timer;sleep 
10;cat /proc/interrupts |grep timer
256:      11200          0     Dynamic-irq  timer0
261:          0       3618     Dynamic-irq  timer1
256:      11472          0     Dynamic-irq  timer0
261:          0       3637     Dynamic-irq  timer1
           CPU0        CPU1

I think they have a lot of differents with Xen 3.0.0. Any comments?

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