----- Original Message -----
From: "Richard W.M. Jones" <rjones@redhat.com> To: "Li Wei" <lw@cn.fujitsu.com> Cc: "Francesco Romani" <fromani@redhat.com>, libvir-list@redhat.com Sent: Tuesday, August 12, 2014 11:04:05 AM Subject: Re: [libvirt] [RFC][scale] new API for querying domains stats
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Is it possible to design an API that can work across all domains in a single call?
How about the following API:
int virConnectGetAllBlockStats(virConnectPtr conn, virDomainPtr domain, virDomainBlockBulkStatsPtr *stats, unsigned int flags); @conn: pointer to libvirt connection @domain: pointer to the domain to be queried, NULL for all domains @stats: array of virDomainBlockBulkStats struct(see below) to be populated @flags: filter flags Return the number of virDomainBlockBulkStats populated.
where virDomainBlockBulkStats defined as:
struct _virDomainBlockBulkStats { virDomainPtr domain; /* domain the block stats belongs to */ virTypedParameterPtr params; /* params to store block stats */ unsigned int nparams; /* how many params used for each block stats */ unsigned int ndisks; /* how many block stats in this domain */ };
Works for me.
Same here. oVirt, more specifically VDSM, needs to check all the stats of all the domains on a given host at once, so this API should fit the task. Since VDSM takes ownership (read: keep track and control) of all the VMs, the filtering capability of this new API should be good enough. +++ It would be nice, but less important, to be able to somehow reuse the `stats' argument. What I'm looking here is a way to avoid to allocate/deallocate every time all the needed structure before and after each call. I'm saying so because is a pretty common scenario for a VM (at least in the cases I'm aware of) to have the same number of disks during all its life. But I believe this is an optimization which can be added later. Thanks, -- Francesco Romani RedHat Engineering Virtualization R & D Phone: 8261328 IRC: fromani