Re: [libvirt] [RFC] New API to retrieve node CPU map
On 10/11/2012 01:01 AM, Viktor Mihajlovski wrote:
No problem to include flags for future extensions to be on the safe
side. However, the map will contain all CPUs with the bits representing
the online/offline state. If the intention is to quickly get the number
of offline/online CPUS the following signature would be better IMO
int
virNodeGetCpuMap(virConnectPtr conn,
unsigned char **cpumap,
unsigned int *online,
unsigned int *offline,
unsigned int flags);
That starts to feel rather complex.
On the other hand, you have a point that returning maplen (number of
bytes allocated in the map) does NOT tell you how many cpus are online
without doing a population count of the result; worse, it cannot tell
you how many cpus are offline (a maplen of 1 is returned whether I have
4 cpus or 8 cpus, so if the map contains the value 0xb, does that mean I
had a 4 cpu machine with cpu2 off, or an 8 cpu machine with cpu2 and
cpu4-7 off?). So allowing the user to optionally ask how many cpus are
online or offline might indeed also be useful, in addition to the maplen
needed to return the bitmap.
--
Eric Blake eblake(a)redhat.com +1-919-301-3266
Libvirt virtualization library http://libvirt.org
Attachments:
- signature.asc (application/pgp-signature — 617 bytes)