On Tue, Aug 05, 2014 at 01:36:02PM +0800, Li Wei wrote:
Hi Richard,
Thanks for your comment!
On 08/04/2014 04:39 PM, Richard W.M. Jones wrote:
On Mon, Aug 04, 2014 at 11:38:41AM +0800, Li Wei wrote:
Hi,
On 07/22/2014 03:25 PM, Richard W.M. Jones wrote:
Did anything come of this discussion, and/or is someone working on this?
I am working on an API to query block stats in a bulk style and proposed an API as follow:
virDomainBlockStatsBulkFlags(virDomainPtr dom, virTypedParameterPtr params, int nparams, int ndisks, unsigned int flags)
@dom: pointer to domain object @params: an array of typed param to be populated with block stats @nparams: how many params used for each block device @ndisks: how many block devices to query @flags: flags to filter block devices (not used for now)
Returns -1 in case of error, 0 in case of success. with params == NULL, nparams == -1, ndisks == 1, return number of params for each block device. with params == NULL, nparams == -1, ndisks == -1, return number of disks in the domain.
A typical usage of this API should be: nparams = virDomainBlockStatsBulkFlags(dom, NULL, -1, 1, 0); ndisks = virDomainBlockStatsBulkFlags(dom, NULL, -1, -1, 0);
params = VIR_ALLOC_N(params, nparams * ndisks);
ret = virDomainBlockStatsBulkFlags(dom, params, nparams, ndisks, 0);
... do something with params
VIR_FREE(params);
With this bulk API, virt-top can updates in a short interval for a domain with a lot of disks. Any comments?
I think this works OK for the case where you have 1 domains with lots of disks.
However if you have a large number of domains each with 1 or 2 disks I think you would have the same problem as currently.
Yes, it is.
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. Please CC me on any patches so I can review them more easily for you. Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-top is 'top' for virtual machines. Tiny program with many powerful monitoring features, net stats, disk stats, logging, etc. http://people.redhat.com/~rjones/virt-top