[libvirt] [PATCH 2/6] util: Introduce virHostCPUGetInfoParseCPUInfo()

[Bjoern Walk]

Andrea Bolognani <abologna at redhat.com> [2017-12-13, 12:34PM +0100]:
> So you'd leave it in virHostCPUGetInfoPopulateLinux()? Why?
> 

I found it more important that all the initialization (cpu, nodes, etc.)
is in one place. But it actually doesn't matter.

> With my approach, the value is changed only in
> virHostCPUGetInfoParseCPUInfo(), which makes IMHO more sense than
> spreading the code that changes it across two functions.
> 
> > > +    /* Start with parsing CPU clock speed from /proc/cpuinfo */
> > > +    if (virHostCPUGetInfoParseCPUInfo(cpuinfo, arch, mhz) < 0)
> > > +        goto cleanup;
> > 
> > Why do we cleanup here and abandon the rest of the information? Since
> > the information in /proc/cpuinfo is kind of volatile in its format,
> > shouldn't we be liberal in what we accept? If we can't parse it, we just
> > report mhz = 0, but gathering the rest of the information in this
> > function is still valuable.
> 
> Most functions in libvirt either perform all tasks succesfully or
> return a failure, so failing here is in line both with that and
> with the existing behavior.
> 

So for example for S390 we have introduced CPU frequency information in
/proc/cpuinfo only recently. That means that depending on your kernel
version, you either read freq. info and the rest of the stuff or you
discard the whole CPU. I found this highly unintuitive.

> -- 
> Andrea Bolognani / Red Hat / Virtualization
> 
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> 

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