[libvirt] [PATCH 1/2] Get cpuMhz of virNodeGetInfo() from cpufreq/cpuinfo_max_freq, if exist

[Minoru Usui]

Hi, Eric

On Mon, 31 Jan 2011 15:46:39 -0700
Eric Blake <eblake at redhat.com> wrote:

> On 01/27/2011 02:51 AM, Minoru Usui wrote:
> > virNodeGetInfo() gets from
> > /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq, first.
> > 
> > Signed-off-by: Minoru Usui <usui at mxm.nes.nec.co.jp>
> 
> I haven't looked closely at this series yet...
> 
> > +    /*
> > +     * nodeinfo->mhz should return maximum frequency,
> > +     * but "cpu MHz" of /proc/cpuinfo is scaled by power saving feature.
> > +     * So it gets cpufreq/cpuinfo_max_freq, if possible.
> > +     */
> > +    ret = get_cpu_value(0, "cpufreq/cpuinfo_max_freq", true);
> > +    if (ret < 0)
> > +	return -1;
> > +    else if (ret != 1) {
> > +	/* convert unit */
> > +	cpu_mhz = ret / 1000;
> 
> But which units is this converting between, and should it truncate or
> round up?

I think it divide by 1000 is collect, because my machine returns below values.

-----------------------------------------------------------------
# cat /sys/devices/system/cpu/cpu?/cpufreq/cpuinfo_max_freq 
2333331
2333331
2333331
2333331
2333331
2333331
2333331
2333331
 
# grep 'cpu MHz' /proc/cpuinfo
cpu MHz         : 2333.331
cpu MHz         : 2333.331
cpu MHz         : 2333.331
cpu MHz         : 2333.331
cpu MHz         : 2333.331
cpu MHz         : 2333.331
cpu MHz         : 2333.331
cpu MHz         : 2333.331
-----------------------------------------------------------------

On the other hand, I don't have clear opinion about truncate or round up. 
Present implementation of linuxNodeInfoCPUPopulate() selects truncate,
so I implement to truncate logic.

-- 
Minoru Usui <usui at mxm.nes.nec.co.jp>