From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeremy Fitzhardinge <jeremy@goop.org>
Subject: Re: Re: [Xen-users] About profiling xen
Date: Thu, 01 Oct 2009 15:01:59 -0700
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To: Marco Tizzoni <marco.tizzoni@gmail.com>
Cc: "Fajar A." <fajar@fajar.net>, Fasiha Ashraf <feehapk@yahoo.co.in>, xen <xen-devel@lists.xensource.com>, xen-users@lists.xensource.com
List-Id: xen-devel@lists.xenproject.org

On 10/01/09 14:55, Marco Tizzoni wrote:
> Sorry, I was not clear. It works as I expect, i.e going not over 1000
> hz (my dom0 kernel has been compiled with 1000hz).
>   

OK, that's definitely *not* expected.  If you're running with
CONFIG_NO_HZ and HIGH_RES_TIMERS then timer resolution should have
nothing to do with your HZ configuration.

> Following a couple of run of your testtimer:
>
> hal9k-dom0 ~ # ./testtimer .000001 |head -n10
>   

I think expecting a timer to work at 1MHz is unreasonable.

> 1000 iterations at  0.000001 sec
> 0.000662
> 0.000946
> 0.000956
> 0.000960
> 0.000962
> 0.000956
> 0.000964
> 0.000963
> 0.000964
> 0.000964
>
> hal9k-dom0 ~ # ./testtimer .00001 |head -n10
>   
100kHz is also very demanding.

How does it work with 2kHz? 10kHz?

    J